Finally, we come to our last alternative listed at the beginning of this SRVCC (Single Radio Voice Call Continuity).

The SRVCC however is not an alternative for delivery, but a rather a handover process of a voice call previously started in the LTE (whether One Voice - VoLTE LTE or IMS Full Voice).

Leonardo Zanoni Pedrini

Telecom Consultant

at Telefônica Brasil

(Telefônica | Vivo)

Everything we have seen so far is based on the making of voice call in the legacy network. But as we have seen these are 'temporary' solutions until the 'final' solution - VoLTE - is available.

And the final LTE voice solution (Voice over IP, or more specifically VoLTE) uses the IMS backbone. An example of network topology supporting VoLTE is shown in the following figure.

Leonardo Zanoni Pedrini

Telecom Consultant

at Telefônica Brasil

(Telefônica | Vivo)

The first implementation alternative that emerged was the VoLGA, tried to use what are already available, with minimal changes required.

To use the infrastructure of legacy 2G/3G networks, VoLGA introduces a new network entity, the VNC (VoLGA Network Controller), which basically functions as a 2G BSC, communicating with a GSM MSC (Mobile Switching Center) and as one 3G RNC communicating with a UMTS MSC (Mobile Switching Center).

Leonardo Zanoni Pedrini

Telecom Consultant

at Telefônica Brasil

(Telefônica | Vivo)

While making a voice call may seem simple, largely depends on the scenario where the user is, and alternatives available for its completion. So it is necessary to understand well what are all the possibilities and the most important concepts of these key scenarios.

Leonardo Zanoni Pedrini

Telecom Consultant

at Telefônica Brasil

(Telefônica | Vivo)