
178 ◾ IP Communications and Services for NGN
A user should be able to change the call characteristics during the course of the
call. is feature is called “call feature changes.”
SIP Networks and Services
SIP for Wireless Networks
SIP is the key to high-value wireless services [21]. e emerging high-value, high-
margin wireless services are about peer-to-peer communications. SIP was designed
to support these types of services. SIP can run on any wireless network.
SIP is used in packet-based IP communications networks, so in the mobile field
it will come into play with the launch of new high-speed 3G systems and through
existing technologies such ...