Voice Over LTE is the next generation voice and video communication over LTE network.

The mobile communication standard Long-Term Evolution (LTE) is optimized for data transfer and designed as a packet switched all-IP system only; it does not include any circuit switched domain currently used for regular voice and SMS services. Demand for mobile broadband services is proven in the increase of data traffic.

Recently, operators have been launching high-speed data networks with LTE technology. However, voice and SMS business still generates around 70% of total operator revenues globally and it has become clear that voice functionality needs to be provided on LTE networks.

With voice over LTE (GSMA VoLTE IR.92 specification, based on global 3GPP standards) as a basis, consumers will be able to use telecom grade voice, video calling and other new richer communication services on LTE smartphones.

How VoLTE Works

In order for voice to run over an LTE network, an IMS (IP Multimedia System) core network needs to provide the telephony service over IP. MMTel (Multi Media Telephony, deployed on the IMS core) is the solution that provides the telephony service (and presence, video calling, chat, etc.) in both LTE and fixed networks. The LTE radio access network and the Evolved Packet Core (EPC) also need to support VoLTE, which can be achieved by software upgrades.

Operators can use the same core network infrastructure (IMS) for VoLTE as for evolved enterprise and consumer services (mobile and fixed convergence over any access).

Consumers will be able to use operator-provided HD voice, video calling and other communication services (chat, presence, and more) on LTE smartphones and other devices. These services use a regular mobile phone number (MSISDN, Mobile Subscriber Integrated Services Digital Network-Number), and VoLTE brings the operator telephony values into an all-IP mobile broadband network: global interoperability, Quality of Service, roaming and seamless mobility, between any mobile devices, over any access. With VoLTE, both voice and LTE data services can be used simultaneously on LTE smartphones.

References

• Voice over LTE by Miikka Poikselkä, Harri Holma, Jukka Hongisto, Juha Kallio, Antti Toskala
• VoLTE: IR.92.V4.0 – IMS Profile for Voice and SMS