Session modification (continued)

Session modification (continued)

The re-INVITE could have been done by either party - it uses the same To, From, and Call-ID as the original INVITE.

Note that the re-INVITEs do not cause a 180 Ringing or other provisional messages, since communication between Alice and Bob is already underway.

Note that the first media session continues despite the SIP signaling, until a new agreement has been reached - at which time the new media session replaces the former session.

The re-INVITE can propose changes of any of the media characteristics, including adding or dropping a particular media stream.

this adding or dropping may be because the user has moved from one wireless cell to another, from one network to another, from one interface to another, from one device to another, …

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Transcript

[slide198] Once they've agreed, then you have the new session, it replaces the old one. Off you go.