VoLTE architecture
VoLTE stands for voice over Long Term Evolution. Utilizing IMS technology, it is a digital packet voice service that is delivered over IP via an LTE access network.
IMS – IP Multimedia Subsystem is a standalone system. It resides out of the LTE network and connected to PDN Gateway through SGi interface.The EPC has three main functional elements.
- The first one is Mobility Management Entity (MME). MME is the single most control point in the EPC and responsible for most of the control plane functions.
- The second in the list is Serving Gateway (S-GW). All IP packets in uplink and downlink flow through S-GW. S-GW is also responsible for handling handovers.
- The last in the list is P-GW or PDN Gateway. P-GW allocates IP addresses to UEs. It also provides interfaces towards internet and IMS.
