Hello All,
Think about the scenarios below :
1) User A calls User B , User B responses with 180, at the same time , User C calls
User A, and User A does want to talk with User C ,what should User A do ?
I think : User A should CANCEL User B first( the dialog between A and B is not
setup yet,the Three HandShake INVITE/200/ACK is incomplete), and response User C with
200 OK, right?
+---------+ +-----------+ +--------+
| User A | | User B | | User C |
+---------+ +-----------+ +--------+
| | |
| 1. INVITE | |
|------------------------->| |
| 2. 180 | |
|<-------------------------| 3. INVITE |
|<-------------------------------------------------|
|User A want to talk with User C |
| 4. 180 | |
|------------------------------------------------->|
| 5. CANCEL | |
| ------------------------>| |
| 6. 200 | |
|<-------------------------| |
| 7. 487 | |
|<-------------------------| |
| 8. ACK | |
|------------------------->| |
| 9. 200 OK |
|------------------------------------------------->|
2) Comparing with 1) , User A calls User B , User B responses with 200 OK, and User A
has not sent ACK to User B, at the same time , User C calls User A, and User A does
want to talk with User C ,what should User A do ?
+---------+ +-----------+ +--------+
| User A | | User B | | User C |
+---------+ +-----------+ +--------+
| | |
| 1. INVITE | |
|------------------------->| |
| 2. 200 OK | |
|<-------------------------| 3. INVITE |
|<-------------------------------------------------|
| User A want to talk to User C
| What should User A do ? send BYE to User B ?
if User A sends BYE to User B , but the Three Handshake INVITE/200/ACK is
also
incomplete( no ACK).
I think , User A should send CANCEL to User B ,right?
Thank you to give me an answer!
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