Unlike previous 3GPP wireless technologies, LTE has no circuit-switched bearer to support voice, so carrying voice over LTE requires a migration to a voice over IP (VoIP) solution – commonly under the umbrella of IMS. Until this migration occurs, LTE-capable handsets need to revert to 2G or 3G for voice calls: an approach that is not ideal in the long term. Driven by major operators, the voice over LTE (VoLTE) ecosystem is maturing rapidly and tracking well to target commercial timelines.

Efforts to validate voice over LTE (VoLTE) from an E2E perspective, which have been under way for more than a year, have the key objective of retaining users.

The industry is progressing rapidly in terms of KPIs, measurement practices and, ultimately, the performance of early voice over LTE (VoLTE) solutions. While some improvements remain to be made, particularly in relation to jitter buffer management (JBM) in the terminal and implementation delays from internal processing in the terminal, the current performance level is already close to, and in some cases superior to the target objectives. LTE schedulers are likely to become more sophisticated in terms of managing mixed voice and data traffic, while ensuring good battery performance.

In short, voice over LTE (VoLTE) works and is ready for widespread adoption.

Validating voice over LTE end-to-end