IMS

Question 1

What is IMS?

Answer 1

is an architectural framework for delivering IP multimedia services. Historically, mobile phones have provided voice call services over a switched-circuit-style network, rather than strictly over an IP packet-switched network. IMS is an architectural framework to provide such standardization.
Facilitate delivery of IP-based multimedia services in cellular
networks

Question 2

SIP

Answer 2

Session Initiation Protocol