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Interexchange carrier

An interexchange carrier (IXC), also known as a long-distance carrier, is a telecommunications company that provides interstate and intrastate toll services, facilitating voice, data, and other communications between different local access and transport areas (LATAs) in the United States.^[1]^[2] These carriers connect end-users through the networks of local exchange carriers (LECs), handling the transmission of calls and signals across geographic boundaries without providing local service within a single LATA.^[3] By federal regulation, an IXC is defined as a telephone company offering toll service, excluding commercial mobile radio service providers.^[1] The role of IXCs became prominent following the 1984 divestiture of the American Telephone and Telegraph Company (AT&T), which ended its monopoly on long-distance services and separated local operations—transferred to seven regional Bell operating companies (RBOCs) as LECs—from interexchange operations assigned to AT&T Communications and emerging competitors.^[4]^[5] This antitrust settlement, stemming from the United States v. AT&T case initiated in 1974, promoted competition by allowing new entrants like MCI and Sprint (originally GTE Sprint) to challenge AT&T's dominance in the interexchange market, where AT&T initially retained about 85% market share post-divestiture.^[6]^[5] Prior to the breakup, long-distance services had been provided almost exclusively by AT&T since the early 20th century, with limited competition emerging in the 1970s through microwave and satellite technologies.^[7] In the contemporary telecommunications landscape, IXCs continue to operate under Federal Communications Commission (FCC) oversight, paying access charges to LECs for originating and terminating calls while complying with universal service obligations as eligible telecommunications carriers.^[8] Major IXCs today include AT&T, Verizon Business (successor to MCI and others), and Lumen Technologies (formerly CenturyLink), though industry convergence with voice over IP (VoIP) and wireless services has blurred traditional distinctions between local and long-distance providers.^[5]^[9] This evolution has reduced the standalone prominence of IXCs, yet the category remains essential for regulating interLATA traffic and ensuring competitive access in a deregulated environment shaped by the Telecommunications Act of 1996.^[10]

Definition and Role

Definition

An interexchange carrier (IXC) is a telecommunications company in the United States that provides long-distance voice and data services, specifically telephone toll service connecting end users in different Local Access and Transport Areas (LATAs).^[11] These carriers are authorized to handle interLATA services, which involve telecommunications between points in different Local Access and Transport Areas (LATAs)—contiguous geographic regions established to delineate the boundaries for local and long-distance calling.^[12] In contrast, intraLATA services occur within a single LATA and are typically managed by local exchange carriers (LECs), while IXCs focus on interLATA toll calls that may be interstate (crossing state lines) or intrastate (within a state but across LATA boundaries).^[13] For example, a call from New York City to Los Angeles would route through an IXC as an interLATA, interstate connection.^[14] IXCs are defined and regulated under the Communications Act of 1934, as amended by the Telecommunications Act of 1996, which established the framework for interstate and foreign communications, including the certification and operational requirements for long-distance providers.^[15] The 1996 amendments further clarified IXC roles by promoting competition, requiring nondiscriminatory access, and integrating them into the broader universal service obligations alongside LECs and other carriers.^[16]

Role in Telecommunications

Interexchange carriers (IXCs) serve as the primary providers of long-distance telecommunications services in the United States, bridging communications between different local exchange areas by transporting traffic between different LATAs, which may cross state lines or occur within a state. They integrate with local exchange carriers (LECs), including incumbent LECs (ILECs), by connecting directly to end offices and tandem switches to originate calls from local networks and terminate them at distant locations. This interconnection enables IXCs to complete end-to-end calls that LECs alone cannot handle due to geographic limitations.^[17]^[18] The service scope of IXCs encompasses traditional voice telephony, data transmission, and an expanding array of Voice over Internet Protocol (VoIP) offerings, allowing users to connect across regional boundaries without relying solely on local infrastructure. By handling interstate and intrastate long-distance traffic, IXCs ensure seamless communication between subscribers served by different LECs, often routing calls through their own backbone networks for efficient transport. This role has evolved to include IP-based services, where IXCs increasingly facilitate VoIP traffic while adhering to intercarrier compensation rules for origination and termination.^[17]^[19] Economically, IXCs compensate LECs through access charges for utilizing local loops and switching facilities, particularly for call termination, which covers the costs of last-mile connectivity. These fees, regulated under frameworks like the 2011 Universal Service Fund/Intercarrier Compensation Transformation Order, promote market competition by enabling multiple IXCs to offer long-distance options to consumers, thereby reducing reliance on a single provider. However, this system can lead to disputes over charge levels, especially in rural areas where higher rates apply to support universal service.^[17]^[18] The interdependence between IXCs and LECs is fundamental to the U.S. telecommunications ecosystem, with IXCs depending on LEC networks for access to end users while LECs benefit from IXC transport capabilities for broader connectivity. IXCs provide the high-capacity backbone infrastructure for long-haul transmission, whereas LECs manage the local distribution, creating a symbiotic relationship that underpins nationwide service reliability. This balance supports competitive dynamics but requires ongoing regulatory oversight to ensure equitable compensation and prevent imbalances like access arbitrage.^[19]^[17]

History

Origins

Prior to 1982, the American Telephone and Telegraph Company (AT&T) maintained a near-total monopoly on long-distance telephone services in the United States through its Long Lines department, which connected regional Bell operating companies and independent telephone providers without any significant competition.^[20] This dominance allowed AT&T to control interexchange services, including interLATA calls between local access and transport areas, while subsidizing local and rural services with profits from long-distance rates.^[20] The monopoly began to erode following the 1982 Modified Final Judgment (MFJ), a court-ordered settlement of a long-running antitrust lawsuit initiated by the U.S. Department of Justice in 1974.^[21] Announced on January 8, 1982, and approved by Judge Harold H. Greene on August 24, 1982, the MFJ required the breakup of AT&T's integrated Bell System, divesting its 22 local operating companies into seven independent Regional Bell Operating Companies (RBOCs), commonly known as the "Baby Bells" or incumbent local exchange carriers (ILECs).^[21] The divestiture took effect on January 1, 1984, allowing AT&T to retain its long-distance operations, Western Electric manufacturing arm, and Bell Laboratories research division, while opening the interexchange market to competition by prohibiting RBOCs from providing long-distance services and mandating equal access for all carriers by September 1986.^[21] The first major non-AT&T interexchange carriers (IXCs) emerged in the late 1960s and 1970s, challenging AT&T's control before the full breakup. Microwave Communications, Inc. (MCI), founded in 1963, received Federal Communications Commission (FCC) authorization in 1969 to construct a microwave relay system between Chicago and St. Louis following the pivotal 1968 Carterfone decision, which permitted non-AT&T equipment interconnections; by 1975, MCI expanded to switched long-distance voice services, establishing itself as the pioneering non-AT&T IXC.^[22] Similarly, Southern Pacific Communications Company (SPCC), originating from the Southern Pacific Railroad's existing lines in the early 1970s, launched competitive long-distance offerings by the mid-1970s under the "SPRINT" brand (Southern Pacific Railroad Internal Networking Telephony), becoming another early IXC and capturing market share from AT&T.^[23] Despite these entrants, AT&T remained the dominant IXC post-breakup, handling the vast majority of long-distance traffic.^[21] In the 1980s, new IXCs like MCI and Sprint encountered substantial barriers to growth, including high access charges imposed by RBOCs to recover costs for local loop connections and subsidies for universal service, which significantly increased the expense of originating and terminating calls.^[24] These charges, initially discriminatory and set above competitive levels by the FCC to equalize access, disadvantaged smaller carriers compared to AT&T, which benefited from established interconnections.^[24] Technical barriers further complicated entry, as RBOCs provided inferior and inconsistent interconnections to new IXCs' networks versus AT&T's, requiring FCC interventions and court orders to enforce MFJ-mandated standards for equal access and quality.^[24]

Deregulation and Evolution

Following the 1984 divestiture of AT&T, the Modification of Final Judgment mandated that local exchange carriers (LECs) provide equal access to all interexchange carriers (IXCs) through Feature Group D service, enabling seamless selection via 10XXX dialing and eliminating the need for customers to use less convenient access methods like 950-XXXX or 950-0XXX.^[25] This requirement, implemented progressively through 1985, leveled the playing field for IXCs by ensuring uniform quality and pricing for exchange access, fostering competition in long-distance services.^[24] The Telecommunications Act of 1996 marked a pivotal deregulation milestone by removing remaining barriers to incumbent local exchange carrier (ILEC) entry into long-distance markets, thereby equalizing competition between IXCs and former Bell Operating Companies (BOCs), also known as "Baby Bells."^[26] Under Section 271, BOCs could offer in-region interLATA services only after FCC approval demonstrating compliance with local competition requirements, such as unbundled network elements and resale obligations; the first such approval was granted to Bell Atlantic (now Verizon) for New York in December 1999, effective in 2000.^[27] This reform accelerated market integration, allowing ILECs to compete directly as IXCs while promoting infrastructure sharing. The IXC industry underwent significant consolidation in the late 1990s and early 2000s, driven by deregulation and the need for scale in a competitive landscape. Notable mergers included WorldCom's $37 billion acquisition of MCI in 1998, approved by the FCC, which created one of the largest IXCs with enhanced national network capabilities.^[28] WorldCom filed for bankruptcy in 2002 amid an accounting scandal, emerging restructured and renamed MCI in 2003; MCI was then acquired by Verizon in 2006 for approximately $8.5 billion (including debt), forming Verizon Business as a major IXC.^[29]^[30] Similarly, AT&T's $86 billion acquisition of BellSouth, completed in December 2006 following FCC approval, further consolidated ILEC-IXC operations post-2005 regulatory reviews, enabling bundled services across wireline and wireless segments.^[31] These consolidations reduced the number of major players from over a dozen to a handful, intensifying efficiency but raising concerns about market concentration. To accommodate the growing number of IXCs, Carrier Identification Codes (CICs)—initially three-digit codes assigned starting in 1983—were expanded to four digits in 1998, with LECs required to complete switch upgrades by January 1 and a phase-out of three-digit codes by September.^[32] This change updated access codes to 101XXXX format, supporting dial-around calling without disrupting presubscribed services. Concurrently, IXCs shifted from analog to predominantly digital networks in the 1990s, deploying fiber-optic systems for higher capacity and reliability; by mid-decade, interexchange transmission was largely digital, with annual fiber deployment growth exceeding 8% among major carriers.^[33]^[34]

Regulation

FCC Oversight

The Federal Communications Commission (FCC) holds primary jurisdiction over interexchange carriers (IXCs) for interstate and foreign telecommunications services under Title II of the Communications Act of 1934, which establishes IXCs as common carriers subject to regulation as such to the extent they provide telecommunications services.^[35]^[8] This authority enables the FCC to oversee IXC operations to ensure just and reasonable rates, practices, and services, while prohibiting unjust or unreasonable discrimination among users. Among its key mandates, the FCC requires IXCs to contribute to the Universal Service Fund based on interstate end-user telecommunications revenues, with quarterly filings via FCC Form 499-Q for carriers exceeding $10,000 in annual contributions; it also enforces local number portability obligations under the Telecommunications Act of 1996, allowing consumers to retain their telephone numbers when switching carriers; and it applies anti-discrimination rules for interconnection to prevent undue preferences or disadvantages in access to networks.^[36] IXCs must comply with reporting requirements, including the filing of tariffs for interstate services by dominant carriers and the cancellation of most tariffs by nondominant IXCs since 2001.^[36]^[37] The FCC enforces compliance through actions such as fines for slamming—unauthorized changes to a consumer's preferred IXC—and cramming—billing for unauthorized services—with notable penalties including an $11 million fine in 2016 against three long-distance carriers for these violations.^[38] Ongoing proceedings, such as the 2019 Access Arbitrage Order in WC Docket No. 18-155, address reforms to curb exploitation of access charges by IXCs and related entities.^[39]

Access Charges and Interconnection

Access charges represent the fees that interexchange carriers (IXCs) pay to incumbent local exchange carriers (ILECs) for the origination and termination of calls using local loops and switching facilities.^[17] These charges were established in the 1980s following the AT&T divestiture to enable cost recovery for local networks while allowing competitive long-distance providers to access end-user connections.^[40] Under the regulatory framework, IXCs compensate ILECs based on per-minute rates for switched access services, which include both end-office and transport elements, as codified in 47 CFR Part 69.^[41] Interconnection obligations for IXCs stem from the Telecommunications Act of 1996, which mandates that local exchange carriers (LECs), including ILECs, negotiate interconnection agreements with requesting carriers such as IXCs to facilitate the exchange of traffic.^[42] These agreements must comply with Section 251 of the Act, requiring nondiscriminatory access at technically feasible points and just and reasonable rates, with state commissions overseeing negotiations and arbitration under Section 252.^[43] For unbundled network elements (UNEs), such as loops and transport facilities, ILECs are obligated to provide them to IXCs and other carriers at forward-looking economic cost-based rates determined through total element long-run incremental cost (TELRIC) methodology, promoting competition by allowing use of incumbent infrastructure without full network duplication.^[44] Tandem switching compensation involves payments from IXCs to LECs for the use of tandem facilities that route calls between end offices and the IXC's network.^[17] Historically, these were tariffed per-minute charges, but reforms have shifted toward bill-and-keep arrangements, where neither party bills the other for terminating local traffic, particularly in the VoIP era to simplify compensation and reduce disputes over traffic direction.^[19] This evolution addresses inefficiencies in legacy systems, with the FCC adopting bill-and-keep as the default for certain traffic types to align with IP-based networks.^[45] Recent reforms include the FCC's 2011 Connect America Fund (CAF) order, which integrated intercarrier compensation changes by capping and gradually reducing terminating access rates for price-cap and rate-of-return carriers over multi-year transitions, while providing recovery mechanisms through universal service support to offset revenue losses for ILECs.^[46] In the 2020s, the FCC has advanced IP interconnection transitions, proposing in a 2025 Notice of Proposed Rulemaking to forbear from legacy TDM interconnection obligations under Sections 251(c)(2) and (c)(6) by December 31, 2028, to eliminate associated access charges and accelerate the shift to all-IP arrangements, thereby reducing regulatory burdens on LECs and IXCs while preserving competitive access through commercial negotiations.^[47]

Operations

Call Handling

Interexchange carriers (IXCs) manage long-distance calls through a structured process that begins with call origination at the local exchange carrier (LEC) level. When an end-user dials a long-distance number prefixed with "1+", the LEC's end office switch detects the toll call and initiates an SS7 (Signaling System 7) query via the Transaction Capabilities Application Part (TCAP) protocol to the Primary Interexchange Carrier (PIC) database, administered by iconectiv. This query retrieves the Carrier Identification Code (CIC) associated with the calling party's presubscribed IXC, enabling the LEC to route the call to the appropriate IXC point of presence (POP).^[48] The LEC then forwards the call signal, including Automatic Number Identification (ANI) for billing purposes, to the IXC's POP switch, typically a tandem switch connected via dedicated trunks.^[49] Upon receiving the call at the IXC POP, the IXC's network—often comprising tandem switches or modern softswitches—processes routing and transport. The IXC authenticates the caller using the received ANI, which identifies the originating telephone number for verification against its customer database, and initiates billing records based on this information. Routing decisions are made using algorithms such as least-cost routing (LCR), which selects the optimal path across the IXC's backbone network to minimize transmission costs while maintaining quality of service, potentially traversing multiple internal switches and utilizing SS7 Initial Address Message (IAM) to reserve circuits. Tandem transit functions aggregate traffic from multiple origins, employing SS7's ISDN User Part (ISUP) for end-to-end signaling to ensure efficient transport without unnecessary hops, as controlled by hop counters in the signaling messages.^[50]^[51] Call termination occurs when the IXC delivers the signal to the distant LEC's access tandem or end office switch via another SS7 IAM, including the called party number and any feature parameters. The terminating LEC completes the connection to the end-user, supporting interactions such as caller ID transmission (via SS7 Calling Party Number parameter) and call waiting alerts, ensuring seamless feature compatibility across networks. For international calls, IXCs route traffic to specialized gateway switches that interface with foreign carriers, often using SS7 or Session Initiation Protocol (SIP) for cross-border signaling and applying country-specific routing tables.^[48]^[50] Throughout the process, IXCs implement error handling protocols to maintain reliability. SS7 includes congestion management via signaling link congestion levels and release cause codes (e.g., code 42 for switching equipment congestion), triggering alternate routing or call rejection announcements to achieve a P.01 grade of service, meaning no more than 1% of calls blocked due to congestion. Fraud detection involves real-time monitoring for ANI/Caller ID mismatches, where discrepancies between the billing ANI and presented caller ID may indicate spoofing or unauthorized usage, prompting call blocking or investigation; IXCs also employ traffic pattern analytics to identify anomalies like access stimulation schemes. In cases of failure, such as unallocated numbers (cause code 1), the IXC issues a release message and may play error tones or announcements to the caller.^[50]^[52]

Network Technologies

Interexchange carriers (IXCs) rely on a robust core infrastructure to aggregate, transport, and interconnect traffic across wide areas. Tandem switches serve as central hubs for traffic aggregation, enabling efficient routing of long-distance calls by interconnecting with local exchange carriers (LECs) and handling billing and recording functions. These switches, often access tandems, facilitate the connection between IXC points of presence (POPs) and LEC end offices, reducing the need for direct trunking to each local switch. Fiber-optic backbones form the high-capacity transport layer of IXC networks, spanning thousands of route miles to carry voice and data traffic with minimal latency and high bandwidth; by the mid-1990s, IXCs had deployed over 107,000 route miles of fiber, supporting the backbone for national and international connectivity.^[53] Points of interconnection (POIs) with LECs occur at physical facilities such as carrier hotels or meet-me rooms, where IXC networks link to LEC infrastructure via fiber cross-connects, enabling seamless traffic exchange and often costing hundreds of dollars monthly per high-speed link. Signaling systems are essential for call setup and management in IXC operations. The Signaling System No. 7 (SS7) has traditionally supported PSTN call setup by providing out-of-band control for routing, billing, and supervision across circuit-switched networks. SS7 enables IXCs to query databases for number portability and route calls efficiently between exchanges. As networks transition to IP-based architectures, SIGTRAN protocols transport SS7 messages over IP using Stream Control Transmission Protocol (SCTP) for reliable delivery, bridging legacy TDM systems with modern IP cores. Diameter has emerged as the successor protocol for IP networks, offering enhanced authentication, authorization, and accounting (AAA) functions in IMS environments, with IXCs adopting it for policy control and charging in converged services. Modern adaptations allow IXCs to integrate voice over IP (VoIP) and emerging technologies for service convergence. VoIP integration employs Session Initiation Protocol (SIP) to establish, modify, and terminate multimedia sessions, translating SIP signaling to SS7 for interconnection with PSTN elements. Softswitches enable the convergence of voice and data by separating call control from media gateways, allowing IXCs to manage hybrid TDM/IP traffic streams efficiently during network migrations. As of 2025, major IXCs continue migrating to fully IP-based networks, with ongoing decommissioning of legacy TDM and SS7 infrastructure to reduce costs and enhance efficiency.^[54] Security and quality mechanisms ensure reliable and protected service delivery on IXC networks. Quality of Service (QoS) mechanisms, such as traffic prioritization and jitter buffers, maintain low latency (<150 ms) and minimal packet loss (<1-3%) for real-time voice traffic, with DiffServ guidelines classifying VoIP flows to prevent degradation. Encryption for VoIP includes Secure RTP (SRTP) using AES for media confidentiality and TLS for SIP signaling protection, mitigating eavesdropping while balancing overhead impacts on QoS. DDoS protection involves stateful firewalls and session border controllers to filter flood attacks, with IPsec tunnels adding resilience against volumetric threats targeting IXC signaling and media paths.

Identification

Carrier Identification Code

The Carrier Identification Code (CIC) is a unique four-digit numeric identifier assigned to interexchange carriers (IXCs) and other entities accessing the local exchange carrier network within the North American Numbering Plan (NANP).^[55] These codes facilitate the routing and billing of long-distance calls in the public switched telephone network (PSTN). For example, AT&T is assigned the CIC 0288.^[56] The structure follows the format XXXX, where each digit ranges from 0 to 9, with codes allocated from separate pools for Feature Group B (FGB) and Feature Group D (FGD) access services.^[55] The assignment of CICs is administered by the North American Numbering Plan Administrator (NANPA) in accordance with guidelines developed by the ATIS-sponsored Industry Numbering Committee (INC), specifically ATIS-0300050.^[55] Eligible applicants, such as local exchange carriers (LECs), competitive local exchange carriers (CLECs), wireless providers, VoIP operators, switchless resellers, or billing clearinghouses, must submit a formal application through the NANP Administration System (NAS), including evidence of regulatory authorization.^[57] For new market entrants in the United States, Federal Communications Commission (FCC) approval is required to verify compliance with telecommunications regulations before assignment.^[58] U.S. entities are generally limited to two FGD CICs per FCC rules, though INC guidelines permit up to six under certain conditions.^[55] In network operations, the CIC is embedded in the Carrier Identification parameter of the SS7 Initial Address Message (IAM) within the ISDN User Part (ISUP) protocol to specify the selected transit network for call routing.^[59] This integration ensures accurate call direction to the designated IXC and supports billing validation, while also helping to prevent unauthorized access by verifying the carrier's legitimacy at network switches.^[60] Historically, CICs were introduced as three-digit codes in 1983 following the AT&T divestiture to identify long-distance carriers.^[32] By the late 1990s, with over 900 carriers entering the market due to increased competition, the three-digit format proved insufficient, prompting an FCC-mandated expansion to four digits.^[61] Existing three-digit CICs were converted by prefixing a leading zero (e.g., XXX to 0XXX), and the transition was phased in during a two-month period from July 1 to September 1, 1998, to accommodate the growing number of participants without disrupting service.^[32]

Presubscription and Selection Methods

Presubscription allows consumers to designate a default interexchange carrier (IXC) for their long-distance calls through their local exchange carrier (LEC), enabling calls dialed with the "1+" prefix to be automatically routed to the selected IXC without additional access codes.^[62] This system was established following the 1984 breakup of AT&T, as part of the Federal Communications Commission's (FCC) equal access mandate, which required LECs to provide non-discriminatory access to all IXCs by September 1986 where technically feasible, promoting competition in long-distance services.^[62] Under presubscription, consumers can change their default IXC at any time, typically by contacting their LEC, which updates the carrier identification code (CIC) in its routing system to reflect the choice. For flexibility without altering the default, consumers can use dial-around services to select an IXC on a per-call basis by dialing specific access codes, such as 10-10-XXX (where XXX is a three-digit CIC) or 101-XXXX (using the four-digit CIC for expanded capacity).^[56] These services emerged in the 1990s to foster greater competition among IXCs, allowing callers to compare rates and choose providers for individual calls, often at payphones or to avoid presubscribed carrier charges.^[63] The Telephone Disclosure and Dispute Resolution Act of 1992 further supported this by directing the FCC and Federal Trade Commission to regulate advertising for dial-around services, ensuring clear disclosure of rates and terms to protect consumers.^[64] To prevent unauthorized changes known as "slamming," FCC rules under 47 CFR § 64.1120 mandate strict verification procedures for any IXC switch, including independent third-party confirmation or written letters of agency, with carriers liable for charges incurred during unauthorized periods.^[65] These protections, strengthened in 2018, apply to telecommunications carriers and require submitting carriers to maintain records of verifications, deterring fraudulent practices in the competitive long-distance market.^[66] Consumers switching IXCs can retain their phone numbers through local number portability, a process mandated by the FCC since 1996, allowing seamless transitions between wireline providers without service interruption.^[67] In modern contexts, traditional presubscription has diminished in relevance due to the rise of voice over Internet Protocol (VoIP) and mobile services, where long-distance selection is often bundled into app-based plans or unlimited wireless packages, eliminating the need for separate IXC designation.^[68] As of June 2024, switched access lines have fallen to 18 million amid 65 million interconnected VoIP subscriptions and 388 million mobile connections, shifting consumer choices toward integrated digital providers rather than legacy presubscription mechanisms.^[68]

Market and Examples

Major Carriers

AT&T has been a dominant interexchange carrier (IXC) in the United States since the 1984 breakup of the Bell System, retaining a leading position in long-distance services through its extensive infrastructure and customer base.^[69] Following the divestiture, AT&T focused on nationwide long-distance operations, achieving a market share of approximately 40% in the 2020s amid the shift toward integrated voice services.^[70] The company offers bundled long-distance capabilities through AT&T Mobility, combining traditional IXC services with wireless and broadband for seamless domestic and international calling.^[71] Verizon Communications emerged as a major IXC from the 2000 merger of GTE Corporation and Bell Atlantic Corporation, creating a robust network spanning local, long-distance, and wireless services.^[72] The company emphasizes fiber-optic backbones and 5G integration to enhance IXC offerings, enabling high-speed long-distance voice transmission over modern IP networks. Verizon's evolution has positioned it as a key provider of enterprise-grade interexchange connectivity, leveraging its legacy assets for reliable nationwide coverage.^[73] Lumen Technologies, formerly known as CenturyLink, serves as a prominent wholesale IXC, specializing in backbone network services that support long-distance traffic for other carriers and enterprises.^[74] Its acquisition of Level 3 Communications in 2017 significantly expanded its global fiber network, adding over 200,000 route miles to bolster interexchange capacity and peering capabilities.^[75] Lumen focuses on high-capacity transport for IXC operations, providing essential infrastructure for voice and data routing across the U.S. and internationally. Among other notable IXCs, T-Mobile has emerged as a significant player following its 2020 merger with Sprint, integrating long-distance services into its mobile ecosystem for competitive bundled offerings. Comcast has developed IXC capabilities through its Xfinity Voice platform, utilizing cable networks to deliver long-distance calling as part of residential broadband packages. International providers like Tata Communications maintain a presence in the U.S. market, offering global interexchange connectivity with ties to subsea cables and enterprise solutions.

Competition and Modern Developments

The interexchange carrier (IXC) sector has experienced substantial market consolidation since the 1990s, when hundreds of providers entered the market following deregulation, leading to intense competition among over 500 authorized IXCs by the mid-1990s. By the 2020s, this landscape has shifted dramatically, with the industry dominated by a smaller number of major players—approximately 20 key entities controlling the bulk of long-distance services—as mergers, acquisitions, and exits reduced fragmentation amid rising operational costs. This consolidation has been exacerbated by a sharp decline in traditional circuit-switched voice services, with switched access lines falling from 34.4 million in December 2020 to 20.6 million in December 2023, at an average annual rate of 15.7%.^[76] The rise of voice over Internet Protocol (VoIP) and over-the-top (OTT) services, such as Zoom, has driven this erosion, as interconnected VoIP subscriptions reached 64.2 million by December 2023 while OTT VoIP accounted for an additional 22.9 million, diverting traffic from legacy IXC networks.^[76] Technological advancements are reshaping IXC operations through widespread migration to all-IP networks, replacing time-division multiplexing (TDM) systems with more efficient packet-based infrastructure to support higher bandwidth and lower costs. The Federal Communications Commission (FCC) has accelerated this transition via its ongoing regulatory efforts, including the 2025 Notice of Proposed Rulemaking to sunset TDM interconnection mandates by December 31, 2028, thereby removing barriers to IP-based peering and collocation. The emergence of 5G networks and edge computing further impacts long-distance services by enabling ultra-low-latency applications and distributed processing, which diminish the role of centralized IXC backhaul in favor of localized data routing for services like cloud gaming and remote collaboration. Regulatory priorities in the 2020s have emphasized expanding broadband access in rural areas, with the Infrastructure Investment and Jobs Act (IIJA) of 2021 allocating approximately $1 billion through the Rural Broadband Connectivity Program to subsidize infrastructure deployment and connectivity for underserved communities.^[77] This focus has intensified competition for IXCs, as competitive local exchange carriers (CLECs) and wireless providers erode their market share; by December 2023, wireless carriers held 386 million voice subscriptions, while cable and other non-ILEC providers captured over 50% of fixed voice lines, bundling long-distance features into broadband and mobile packages.^[76] Looking forward, the IXC sector anticipates growth in international services, driven by rising demand for global data interconnectivity and cross-border calling, projected to expand as multinational enterprises leverage hybrid cloud environments. Innovations like AI-driven routing are emerging to optimize traffic management, predict network congestion, and enhance efficiency in IP-based systems. However, ongoing debates over net neutrality, following the FCC's April 2024 restoration of Title II classification for broadband providers (effective mid-2025), pose challenges by potentially imposing stricter oversight on IXC data practices and interconnection agreements.

References

[1]
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Interexchange Carrier (IXC) is a communications common carrier that provides telecommunications services between local access and transport areas (LATAs)
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[20]
Updating the Intercarrier Compensation Regime To Eliminate ...
Jun 1, 2023 · Interexchange carriers are required to pay LECs for access to their networks, and in the case of calls to customers located in rural areas, IXCs ...
[21]
[PDF] June 23, 2022 FCC FACT SHEET* Updating the Intercarrier ...
Jun 23, 2022 · (b). Carrier's carrier charges shall be computed and assessed upon all Interexchange Carriers that use local exchange switching facilities for ...
[22]
The Breakup of "Ma Bell": United States v. AT&T
United States v. AT&T was dismissed on August 24, 1982, and the divestment of AT&T's local operating companies was implemented on January 1, 1984.
[23]
AT&T Divestiture - Bell System Memorial
The 471-page filing details how the company proposes to divest, as of Jan. 1, 1984, the assets, work force and stock ownership of the Bell System's 22 operating ...
[24]
The History of MCI (Microwave Communications, Inc.)
The infamous Carterfone case in 1968 that allowed interconnections between private systems and the AT&T phone network was instrumental for MCI as it was able to ...Missing: interexchange | Show results with:interexchange
[25]
The History of SPRINT (long distance, local, and wireless)
Sep 24, 2023 · In the early 1970s, the company began looking for ways to use its existing communications lines for long-distance calling. This division of ...
[26]
[PDF] A LESSON FROM THE LANDMARK AT&T BREAKUP:
above, the Modified Final Judgment or MFJ, as it is more commonly known. The decree had to address two major policy and practical goals. The first goal was ...
[27]
[PDF] Modification of Final Judgment: U.S. v. Western Electric Company ...
Aug 24, 1982 · Whenever, as permitted by this Modification of Final Judgment, a BOC fails to offer exchange access to an interexchange carrier that is equal ...
[28]
[PDF] Telecommunications Deregulation Issues and Impacts
The 1996 Act rendered monopoly franchises illegal for local exchange carriers, permitted Regional Bell Operating Companies (RBOCs) to provide long-distance.
[29]
Federal Register, Volume 64 Issue 250 (Thursday, December 30 ...
Dec 30, 1999 · Bell Atlantic demonstrates that it will comply with the requirements of section 272. Pursuant to section 271(d)(3), Bell Atlantic must ...<|separator|>
[30]
News Release: FCC Approves Merger of WorldCom and MCI
The Commission today approved the transfer of communications licenses and authorizations from MCI Communications Corp. to WorldCom, ...
[31]
BellSouth Corporation - Investor Relations | AT&T
BellSouth became a wholly owned subsidiary of AT&T Inc. The acquisition was completed on December 29, 2006.
[32]
CCB Page Template - Federal Communications Commission
Jul 29, 1998 · Three-digit CICs are being expanded to four-digits by adding an initial "0." Thus, the five-digit CAC "10XXX" will now become the seven-digit ...
[33]
PART 1--SETTING THE STAGE - The National Academies Press
At that time we had digital carriers starting to link the analog switches in the bowels of the network. ... All interexchange transmission is digital and optical.
[34]
[PDF] FCC RELEASES FIBER DEPLOYMENT UPDATE The FCC has ...
Jul 19, 1996 · Current estimates indicate that interexchange carriers increased their deployed fiber by about 8% during 1995. The Bell operating companies' ...Missing: shift authoritative
[35]
[PDF] Communications Act of 1934
(10) COMMON CARRIER.--The term ''common carrier'' or ''carrier'' means any person engaged as a common carrier for hire, in interstate or foreign communication ...
[36]
Common Carrier Filing Requirements - Information for Firms ...
May 18, 2021 · This list provides information on the most common requirements for interstate and international telecommunications carriers.<|control11|><|separator|>
[37]
Policy and Rules Concerning the Interstate, Interexchange ...
Apr 16, 2001 · ... common carriers to offer consumers bundled packages of ... interexchange carriers, including the nondominant interexchange affiliates ...
[38]
FCC Fines Companies $11M For Slamming, Cramming, Deceptive ...
Sep 15, 2016 · The Federal Communications Commission today announced $11 million in fines against three related long distance carriers for "cramming," ...
[39]
[PDF] Orders TOC by Paragraph.dot - Federal Communications Commission
Sep 27, 2019 · The record reflects that in Iowa and South Dakota, much access stimulation traffic is bypassing CEA networks pursuant to commercial agreements, ...
[40]
Access Charge Reform Section 1
In 1983, following the decision to break-up AT&T, the Commission adopted uniform access charge rules in lieu of earlier agreements.Missing: 1980s ILECs
[41]
47 CFR Part 69 -- Access Charges - eCFR
47 CFR Part 69 establishes rules for access charges for interstate or foreign telephone services, including how they are computed and collected.
[42]
Telecommunications Act of 1996 - Congress.gov
... carrier is making available public switched network infrastructure and functions under this section. ... carriers reselling telecommunications services ...
[43]
47 U.S. Code § 251 - Interconnection - Law.Cornell.Edu
The duty to afford access to the poles, ducts, conduits, and rights-of-way of such carrier to competing providers of telecommunications services on rates, terms ...Missing: IXCs | Show results with:IXCs
[44]
Unbundled Access to Network Elements; Review of the Section 251 ...
Feb 24, 2005 · In this document, the Federal Communications Commission (Commission) adopts rules concerning the unbundling obligations of incumbent local ...
[45]
8YY Charge Reform - Federal Register
Nov 27, 2020 · ... tandem switching and transport rates to bill-and-keep. The Commission has previously delineated the merits of bill-and-keep as a rate ...
[46]
Connect America Fund; A National Broadband Plan for Our Future ...
Dec 16, 2011 · This is information will help the Commission to comprehensively reform and modernize the universal service and intercarrier compensation systems.Connect America Fund for... · Limits on Reimbursable... · Modeling Limits on...
[47]
[PDF] Advancing IP Interconnection Notice of Proposed Rulemaking
Oct 7, 2025 · What interconnection arrangements do carriers subject to the rural exemption under section 251(f)(1) or (f)(2) have for TDM or IP voice services ...
[48]
[PDF] Signaling System 7 (SS7) - CS-Rutgers University
Signaling System 7 (SS7) is an architecture for performing out-of-band signaling in support of the call-establishment, billing, routing, and information- ...
[49]
[PDF] Federal Communications Commission FCC 20-143 Before the ...
Oct 9, 2020 · Exchange Carriers and Interexchange Carriers et al., CC Docket No. 00-256 et al., Second Report and Order and. Further Notice of Proposed ...
[50]
[PDF] Intercarrier Call Completion/Call Termination Handbook | ATIS
SS7 Inter Network Trunk ... Multiple entities will be involved in routing for all calls except those that originate and terminate within the network.
[51]
Least cost routing challenges | TransNexus
Least Cost Routing, or LCR, is a process to find the most inexpensive way to route phone calls. This whitepaper reviews LCR techniques.
[52]
[PDF] A Survey of Techniques Against Telephone Spam - SoK papers
A spammer could defeat Caller ID Anomaly Detection by carefully crafting the caller ID to not trigger any known anomalous patterns. ANI-CPN Matching checks ...
[53]
Carrier Identification Codes (CIC) | NANPA
Carrier Identification Codes (CICs) are used to route and bill calls in the public switched telephone network. CICs are four-digit codes in the format XXXX.Missing: expansion 3- 1983 1998
[54]
[PDF] Long Distance Carrier Code Assignments
Carrier Identification Codes (CICs) identify long distance carriers for billing and routing traffic. Customers use them to reach alternative providers. Codes ...<|control11|><|separator|>
[55]
None
### Summary of CIC Structure and Assignment Details
[56]
[DOC] DA-03-2765A1.doc - Federal Communications Commission
Carrier Identification Codes are assigned to carriers by the North American Numbering Plan Administrator (NANPA) in accordance with the Industry Numbering ...<|control11|><|separator|>
[57]
Dialogic Integrated Media Gateways - Sangoma Documentation
Mar 17, 2025 · Carrier Identification Code: CIC This parameter indicates the specific transit network selected by the originating subscriber. The CIC ...
[58]
Carrier Identification Codes (CIC): How They Work for ... - Bandwidth
Jul 27, 2018 · CIC, short for “Carrier Identification Code,” is a unique four-digit code given by the North American Numbering Plan Administrator (NANPA) to carriers and ...
[59]
NORTH AMERICAN NUMBERING PLAN CARRIER ...
Issued Declaratory Ruling to allow a phase-out of three-digit CICs over a two month period beginning July 1, 1998 and ending September 1, 1998.Missing: expansion 4
[60]
[PDF] Federal Communications Commission Record
The letter of agency must be signed and dated by the subscriber to the telephone line(s) re- questing the primary interexchange carrier change. (c) The letter ...
[61]
Local, Local Toll, and Long Distance Calling
Dec 31, 2019 · Local exchange is within a local area. Local toll is within a LATA, including calls outside your exchange. Long distance is outside local and ...
[62]
Joint FCC/FTC Policy Statement for the Advertising of Dial-Around ...
Jul 17, 2000 · In 1992 Congress passed the Telephone Disclosure and Dispute Resolution Act (“TDDRA”), directing the FCC and the FTC to issue regulations ...Missing: 1990s | Show results with:1990s
[63]
47 CFR 64.1120 -- Verification of orders for telecommunications ...
In accordance with the procedures set forth in 64.1120(a)(1)(ii), submitting carriers shall maintain and preserve audio records of verification of subscriber ...
[64]
[PDF] Federal Communications Commission FCC 18-78
Jun 8, 2018 · Today, we amend our rules to reinforce the Commission's ability to take action against slammers and crammers and to deter carriers from slamming ...
[65]
Porting: Keeping Your Phone Number When You Change Providers
Nov 17, 2023 · You can keep your existing phone number. This process – often referred to as phone number porting – can be done between wireline, IP and wireless providers.More Consumer Information · Getting The Porting Process... · Porting Is Not Always...
[66]
[PDF] Voice Telephone Services: Status as of June 30, 2024
In June 2024, there were 18 million end-user switched access lines in service, 65 million interconnected VoIP subscriptions, and 388 million mobile ...
[67]
The AT&T Divestiture: Was It Necessary? Was It a Success?
Jan 5, 2024 · AT&T divestiture exposed the folly of the FCC's pricing policy and forced it to reduce access charges after 1984.
[68]
AT&T's Decline: How Geographic Fragmentation Reshaped a ...
Aug 17, 2023 · From 1984 to 1996, AT&T's share of total long-distance revenues dropped from 90.96 percent to 47.9 percent. Meanwhile, MCI took the largest ...
[69]
[PDF] Complete Annual Report 2024 - Investor Relations | AT&T
Apr 4, 2025 · Based on the closing price of $19.11 per share ... We are a leader in providing connectivity services through our market focus areas of 5G and ...
[70]
GTE - Verizon
GTE Corp. merged with Bell Atlantic Corp. to become Verizon Communications Inc. on June 30, 2000. Prior to the merger, GTE had been the largest independent ...
[71]
[PDF] Major Events Overview | Verizon
The merger of Bell Atlantic and GTE, to form Verizon Communications, became effective on June 30,. 2000, with an exchange ratio of 1.22 shares of Verizon ...
[72]
CenturyLink completes acquisition of Level 3 - PR Newswire
Nov 1, 2017 · MONROE, La., Nov. 1, 2017 /PRNewswire/ -- CenturyLink, Inc. (NYSE: CTL) has completed its acquisition of Level 3 Communications, Inc.
[73]
CENTURYLINK TO ACQUIRE LEVEL 3 COMMUNICATIONS - Lumen
Oct 31, 2016 · CenturyLink will acquire Level 3 for $34 billion, with $26.50 per share in cash and 1.4286 CenturyLink shares per Level 3 share. The combined ...