What is basic difference between VoLGA and SRVCC ?

Question

As we know, when a session is established between two user agents i.e. UAC (User Agent Client) and UAS (User Agent Server), known as Dialog in SIP terminology. I read that a SIP user agent client can trigger INVITE message towards user agent server in an already established session. This scenario is known as "re-invite" but I am unable to think the case in which it happens.

Answer 1

Both VoLGA and SRVCC used to serve voice for LTE users.
VoLGA is used where IMS is not present in network. If IMS is placed in network then SRVCC is being used to provide voice services using VOIP within LTE network. but In VoLGA case voice services is provided through legacy CS network like GSM/UMTS.

Comments

is there any other difference you can point out to me