What is the correct behavior for a proxy in the following situation?
According to bis09, User A should not send the CANCEL (F6) until
it has first received a 100 response from the Proxy. However,
there are user agents out there that violate this.
My question is how should the stateful proxy behave?
Should it send out a CANCEL to any targets that have already had
the INVITE sent to them and send a 200 (for Cancel) back to the caller?
If the invite has not yet been received, (messages crossed) should it
ignore the CANCEL?
Here is a possible call flow. F3 should not be sent until F5 has been
received. However, we have seen several examples where this is not the case.
User A Proxy 1 User B
| | |
| INVITE F1 | |
|--------------->| INVITE F2 |
| CANCEL F3 |--------------->|
|--------------->| 180 F4 |
| (100) F5 |<---------------|
|<---------------| |
| 200 F6 | |
|<---------------| CANCEL F7 |
| |--------------->|
| | 200 F8 |
| |<---------------|
| | 487 F9 |
| |<---------------|
| | ACK F10 |
| 487 F11 |--------------->|
|<---------------| |
| ACK F12 | |
|--------------->| |
| | |
Jason
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