Telephony services over LTE end-to-end

How to deliver telephony services for LTE-capable devices is a topic of much debate. There are two standardized solutions that Ericsson supports for delivering these services – IMS Multimedia Telephony and circuit-switched fallback for operators that have not yet migrated to IMS/MMTel.

Although LTE is a packet-only technology, the standard was defined to efficiently handle voice and multimedia services, providing support for more than mobile internet access.

This article describes how Ericsson and telecommunications standardization bodies envision the realization of telephony services over LTE/EPC.

The authors take an end-to-end perspective, outlining requirements in the LTE radio access, EPC, IMS core, and MMTel application server. They describe IMS features for voice telephony, media handling, radio features for voice, QoS quality, roaming architecture, emergency calls, and solutions that coexist with circuit-switched infrastructure.

The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) standard promises to deliver efficient mobile broadband and multimedia communication services. In keeping with this objective, it was developed to include the features needed to effectively support voice-over-IP (VoIP) media and control. How telephony services are to be realized over LTE, however, has been hotly debated in recent years.

Ericsson stands behind the two solutions standardized by 3GPP, namely IP Multimedia Subsystem (IMS) Multimedia Telephony (MMTel) and circuit-switched fallback (CSFB). Ericsson is promoting MMtel as the main telephony-over-LTE solution because it fulfills all the requirements of a telephony solution. What is more, it is future-proof, allowing an evolution from today’s voice and video telephony to full-fledged multimedia communication.