Hi,
There are two scenarios to consider

a)If UA1 does not receive any provisional response, it should not send any
Request. Thus it shouldnt send CANCEL or INFO(Section 13.2.1 line: 2116
bis-09)

b)
UA1<---1xx Response---UA2
UA1--->CANCEL--UA2
UA1<---200 INVITE-----UA2
If UA1 receives any provisional response and sends CANCEL, and receives a
200 Response as shown above, it MAY send a BYE(Section 15 bis-09 line: 2370)

>How will UA2 know whether the CANCEL was for INFO or for INVITE ?
Through CSeq No. INFO will have an incremented CSeq No

Salman Abdul Baset
Design Engineer
Avaz Networks
[EMAIL PROTECTED]


>1. Cancel for Info (Vijeth  D)

>Hi,
>   Consider the following scenario.
>  UA1 sends Invite to UA2
>  UA2 sends 200 OK but before it reaches UA1, UA1 generates 
>CANCEL. ( 200 and CANCEL "on the wire" ).
>Now UA1 ACKS UA2 and sends an INFO.
>If the INFO reaches UA2 and then the CANCEL arrives.
>How will UA2 know whether the CANCEL was for INFO or for INVITE ?

>Thanks and Regards,
>Vijeth


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