UE#1 builds an SDP offer containing bandwidth requirements and characteristics for
each set of codecs that it is capable of supporting for this session. It assigns local port numbers for
each possible media flow.
UE#1 is willing to establish a multimedia session comprising a
video stream and an audio stream. The video stream supports two codecs, either H.263 or MPEG-4
Visual. The audio stream supports the AMR codec.
contains the international E.164 number from the user.
Via: contains the IPv6 address or FQDN (fully qualified domain name)
of the originating UE.
Route: contains the P-CSCF address learnt during P-CSCF discovery,
plus the elements from the
Service-Route header from registration. The P-CSCF URI contains the port number learnt
during the security agreement negotiation.