The landscape of mobile communication continues to evolve rapidly, and Code Division Multiple Access (CDMA) technology is no exception. As we move into 2024 and beyond, emerging standards and protocols are shaping the future of CDMA networks, aiming to enhance speed, security, and interoperability. While LTE and 5G dominate headlines, CDMA remains a critical backbone in many regions, supporting legacy systems and specialized applications. This article explores the key standards, protocols, and industry trends that will define CDMA in the coming years, providing stakeholders with a roadmap for modernization and coexistence.

Historical Context and the Ongoing Relevance of CDMA

CDMA emerged as a revolutionary air interface in the 1990s, enabling networks such as IS-95 (cdmaOne) and later IS-2000 (CDMA2000). Its spread-spectrum technique allowed multiple users to share the same frequency band simultaneously, offering significant capacity and call quality advantages over earlier TDMA-based systems. By the early 2000s, CDMA became the foundation for 3G networks worldwide, with operators like Verizon, Sprint, and China Telecom relying on it for voice and data services.

Today, CDMA networks are in decline, but they are far from extinct. According to the CTIA, CDMA still serves tens of millions of subscribers in North America, parts of Asia, and Africa. Many operators maintain CDMA infrastructure for rural coverage, machine-to-machine (M2M) communications, and as a fallback for voice calls during LTE outages. The technology’s low latency and wide coverage make it ideal for certain IoT applications, including fleet tracking and utility metering.

In 2024, the focus is not on building new CDMA networks but on integrating existing assets with modern protocols. This approach allows carriers to delay costly spectrum refarming while supporting legacy devices. The emerging standards and protocols described below are designed to bridge the gap between old and new, ensuring that CDMA remains a viable piece of the telecommunications puzzle for years to come.

Key Emerging Standards for 2024 and Beyond

Enhanced Voice and Data Protocols: VoLTE, VoNR, and 1xAdvanced

Voice over LTE (VoLTE) and Voice over New Radio (VoNR) have become the default voice solutions for 4G and 5G networks. However, many CDMA operators still rely on circuit-switched voice for their legacy subscribers. The emerging standard for voice interworking is Single Radio Voice Call Continuity (SRVCC), which allows a VoLTE call to seamlessly hand over to a CDMA 1xRTT circuit-switched network when LTE coverage ends. Enhanced versions of SRVCC, such as eSRVCC, reduce handover delay to less than 100 milliseconds, preserving call quality.

On the data side, the CDMA2000 1xEV-DO Rev. A/B standard has been further evolved into 1xAdvanced, which incorporates multi-carrier aggregation and higher-order modulation (up to 64-QAM). These improvements yield peak data rates of 3.1 Mbps per carrier, making CDMA data usable for basic web browsing and M2M telemetry. Operators can pair 1xAdvanced with eHRPD (Evolved High Rate Packet Data) to provide a smooth transition path to LTE. eHRPD acts as a bridge, allowing users to move between CDMA and LTE networks without losing data sessions.

Another significant development is the integration of CDMA with 5G New Radio (NR). The 3GPP standards body, via Release 17 and later, has defined interworking mechanisms that allow a 5G standalone (SA) core to authenticate and register a CDMA device through a gateway. While this is not a full CDMA-to-5G air interface, it enables operators to reuse their CDMA subscriber databases and billing systems while gradually migrating users to 5G.

Interoperability Standards for Seamless Handovers

Interoperability remains the highest priority for operators running multi-technology networks. The 3GPP Inter-RAT (Radio Access Technology) Handover specification (TS 23.216) outlines procedures for moving active sessions between CDMA, LTE, and 5G. Key standards and features include:

  • CSFB (Circuit Switched Fallback): Allows an LTE device to switch to CDMA for voice calls when VoLTE is unavailable. This is critical in areas where LTE voice coverage is thin.
  • SRVCC/eSRVCC: As mentioned, provides voice continuity from LTE to CDMA. Newer iterations support SRVCC from 5G to CDMA via a fallback to LTE first.
  • IMS (IP Multimedia Subsystem) Interworking: The IMS core supports multiple access networks, including CDMA (via a P-CSCF interface). This enables consistent multimedia services such as push-to-talk, video telephony, and conferencing across CDMA and IP networks.
  • ANSI-41 and MAP Signaling Interoperability: Updates to the signaling protocols used for mobility management and call control ensure that CDMA’s IS-41 (ANSI-41) can communicate with LTE’s Diameter-based protocols through a signaling gateway.

These standards are continuously refined in 3GPP and 3GPP2 collaboration groups. The result is a network ecosystem where a user can start a call on 5G, move to LTE, and fall back to CDMA without any perceptible interruption.

Security Enhancements for CDMA Networks

Security has historically been a weak point for CDMA. The original CAVE authentication algorithm is considered obsolete and vulnerable to cloning and eavesdropping. Emerging standards mandate the use of Advanced Encryption Standard (AES) for both voice and data encryption. The UIM (User Identity Module) has been updated to support the Java Card platform and stronger mutual authentication, preventing phone or SIM cloning.

In 2024, operators are expected to enforce the following security protocols on CDMA networks:

  • AES-128 for 1x and EV-DO traffic: Replaces the older ORYX and CMEA encryption algorithms.
  • IPsec for signaling between CDMA RAN and core: Encrypts A-bis and A-interfaces to prevent interception of control messages.
  • MAPsec: Secures SS7-based signaling within CDMA networks, mitigating attacks such as SMS interception and location tracking.
  • Device certificate validation: Using a Public Key Infrastructure (PKI) to ensure only authorized devices connect to the network.

These enhancements are especially important for mission-critical CDMA applications in utilities, military, and healthcare, where data integrity and user privacy are paramount.

Protocols Driving the Modernization of CDMA

IP Multimedia Subsystem (IMS) – The Converged Control Layer

IMS is the backbone of all modern telecom services, enabling voice, video, and messaging over IP. For CDMA operators, IMS provides a path to decouple call control from the radio access technology. By deploying an IMS core, a carrier can serve subscribers on CDMA, LTE, and Wi-Fi using the same service logic.

The key IMS components relevant to CDMA include:

  • P-CSCF (Proxy-Call Session Control Function): Acts as the entry point for CDMA devices, converting proprietary signaling into SIP (Session Initiation Protocol).
  • AGCF (Access Gateway Control Function): Bridges the legacy CDMA MSC (Mobile Switching Center) with the IMS network, allowing a seamless handover between circuit-switched and packet-switched domains.
  • MRF (Media Resource Function): Provides announcements, transcoding, and conferencing services for CDMA users connected via IMS.

Adopting IMS allows operators to retire legacy circuit-switched equipment gradually while maintaining full service capability. Many Tier-1 carriers have already completed IMS deployments for CDMA, and smaller operators are expected to follow in 2024-2025 as equipment costs decline.

Single Radio Voice Call Continuity (SRVCC) – The Handover Lifeline

SRVCC is perhaps the most critical protocol for CDMA’s survival in the LTE/5G era. It defines how a voice call initiated in a packet-switched domain (VoLTE) can be transferred to a circuit-switched domain (CDMA) without interruption. The protocol operates at the MME (Mobility Management Entity) and MSC levels.

Enhanced SRVCC (eSRVCC) reduces handover time through early media forwarding and pre-reservation of resources in the target cell. This improvement is vital for highway driving scenarios where coverage changes quickly. SRVCC for CDMA is supported in 3GPP Release 9 and later. For 5G, a variant called vSRVCC (Video SRVCC) allows video calls to transition from LTE/5G to CDMA by dropping the video component and preserving audio.

Operators planning to sunset CDMA entirely must ensure that SRVCC remains robust until the last subscriber is migrated. Many have set sunset dates in 2025-2026, but delays are common due to IoT devices and rural customers reliant on CDMA-only handsets.

NB-IoT and LTE-M – Complementing CDMA for the Internet of Things

CDMA has long been the technology of choice for low-data M2M applications, from smart meters and vending machines to vehicle telematics. However, the rise of narrowband IoT standards has provided a more cost-effective and scalable alternative. LPWAN technologies such as NB-IoT (Narrowband IoT) and LTE-M (LTE for Machines) offer better spectral efficiency, longer battery life (10+ years), and deeper indoor penetration.

Nevertheless, CDMA remains entrenched in many existing M2M deployments. The emerging protocols therefore focus on dual-mode operation where a single modem chipset can support both CDMA and NB-IoT/LTE-M. The 3GPP Release 14+ specifications define a common core network interface that allows these devices to be managed via a single IoT platform.

Key aspects of this convergence include:

  • M2M interworking gateway: Translates CDMA’s older Data Burst messages (used for short messages in power-saving mode) into modern CoAP or MQTT formats.
  • Seamless roaming between CDMA and LTE-M: Devices can switch networks based on coverage area without re-registering with the application server.
  • Energy-efficient mode changes: Using eDRX (extended Discontinuous Reception) on LTE-M while modern CDMA devices can use a similar idle mode mechanism inherited from EV-DO.

This coexistence strategy allows enterprises to gradually migrate their IoT fleets from CDMA to next-generation networks without a forklift upgrade of all devices.

Enhanced Single-Carrier and Multi-Carrier Data Protocols

Although CDMA data rates are far below LTE, operators can still optimize their spectrum through advanced radio protocols:

  • Multi-Carrier EV-DO (MC EV-DO): Combines up to four 1.25 MHz carriers for aggregate data rates exceeding 12 Mbps. Though modest by modern standards, this is sufficient for fixed wireless access in underserved areas.
  • Enhanced Forward Link Trilateration (EFLT): Improves location-based services running on CDMA networks, a requirement for E911 compliance and fleet management.
  • Adaptive Modulation and Coding (AMC): Lets the base station dynamically adjust modulation (QPSK, 8-PSK, 16-QAM, 64-QAM) based on real-time channel conditions, increasing throughput in favorable environments.

These protocols are fully backward-compatible with existing CDMA hardware, meaning operators can deploy them via software updates to base station controllers.

Implications for Stakeholders

Telecom Operators and Service Providers

For carriers, the emerging CDMA standards offer a controlled migration path. Rather than immediately decommissioning CDMA, operators can:

  • Delay capital expenditure on spectrum refarming by extending CDMA’s life using IMS and SRVCC.
  • Maintain rural coverage where CDMA’s larger cell size provides economic advantages over LTE/5G.
  • Leverage CDMA for M2M services where device churn is low and interoperability with legacy equipment is valued.

Challenges include the waning availability of spare parts for CDMA base stations, rising energy costs for older equipment, and the need to train staff on multi-technology interworking. Operators must carefully balance the cost of maintaining CDMA against the risk of losing customers to competitors who offer seamless next-generation coverage.

Device Manufacturers and Chipset Vendors

Chipset makers such as Qualcomm, MediaTek, and Intel have largely stopped designing new CDMA-only modems. However, they continue to produce multi-mode chipsets that include CDMA alongside LTE and 5G. These chipsets are essential for global roaming and for markets like China where CDMA remains active. The emerging demand is for:

  • Low-cost IoT modems that combine CDMA with NB-IoT on a single die.
  • Smartphones that support full CDMA-LTE-5G interworking to satisfy carrier certification requirements.
  • Firmware updates that enable eSRVCC and IMS registration for existing CDMA devices.

Device makers must also navigate varying sunset timelines across regions. For example, Verizon announced a CDMA sunset in 2022, but its implementation has been staggered, and many CDMA-only IoT devices remain active via roaming agreements. Standards for device provisioning and Over-the-Air (OTA) updates are crucial to manage this transition smoothly.

End Users and Enterprise Customers

Consumers should expect improved call reliability due to eSRVCC and VoLTE integration, even in CDMA coverage areas. For enterprises, the security upgrades mean that sensitive data transmitted over CDMA is now protected with AES-level encryption, making it permissible for healthcare and financial transactions. Additionally, companies with large installed bases of CDMA M2M devices can now look forward to a gradual migration path that avoids immediate rip-and-replace.

Rural customers, in particular, benefit from continued CDMA coverage coupled with LTE overlay. The combination ensures that voice calls remain clear while data speeds gradually improve as the operator densifies the LTE network using the same frequency bands.

Regulatory and Industry Collaboration Efforts

The shift to modern CDMA standards is supported by work within the 3GPP (Release 17 and 18) and the 3GPP2. Key collaborative outputs include interoperability test plans, reference architectures for IMS integration, and guidelines for security upgrades. The CTIA in the United States and the GSMA worldwide also provide best practices for CDMA network evolution through their Future Networks Program.

Regulators in markets with significant CDMA presence (e.g., India, South Korea, China) have set aside spectrum resources to allow carriers to operate CDMA alongside LTE until natural subscriber attrition occurs. The International Telecommunication Union (ITU) has also published recommendations for the evolution of IMT-2000 systems, which include CDMA2000 and its enhancements.

Challenges and Considerations for Long-Term Viability

Despite the progress, CDMA faces several headwinds:

  • Ecosystem Decline: Fewer OEMs produce CDMA infrastructure, and spare parts become scarcer and more expensive each year.
  • Spectrum Refarming: Regulators pressure operators to clear CDMA from valuable low-band frequencies (e.g., 850 MHz, 900 MHz) for 5G deployment.
  • Battery Life Limitations: Old CDMA modems drain batteries faster than modern LTE-M or NB-IoT, discouraging new IoT deployments.
  • Skill Gap: Engineering talent familiar with CDMA’s intricate signaling and RF planning is retiring, and younger engineers focus on 4G/5G.

Operators must therefore plan for eventual CDMA sunset, even as they adopt the emerging standards. A sensible strategy is to migrate voice subscribers to VoLTE with CDMA fallback, while IoT devices are gradually replaced with dual-mode modems. The new protocols buy time—perhaps 3 to 5 more years—for operators to execute this transition without service disruption.

Looking Ahead: CDMA in the 5G and 6G Eras

In 2024 and beyond, CDMA will no longer be a primary technology, but it will persist as a specialized overlay in grid modernization, aviation communication, and military tactical networks. Standards bodies are also exploring CDMA-derived waveforms for 6G integrated sensing and communication (ISAC), which could reuse CDMA’s spread-spectrum properties for joint radar and data functions. Academic research into sparse code multiple access (SCMA) and non-orthogonal multiple access (NOMA) draws on CDMA’s core concept but adapts it for massive MIMO and high-frequency bands.

Thus, while the CDMA networks of today are fading, the philosophy behind CDMA—code-based, non-orthogonal sharing of resources—persists in the next generation of air interfaces. The standards and protocols emerging now ensure that the investments in CDMA infrastructure and expertise are not wasted but serve as a stepping stone to a more interoperable, secure, and efficient future.

For fleet publishers and mobile industry observers, understanding these developments is critical. They shape how millions of subscribers will experience connectivity in the coming years—bridging the gap between generations, maintaining service continuity, and enabling graceful technology transitions. By staying informed about these evolving standards, stakeholders can make strategic decisions that maximize the return on legacy assets while embracing innovation.