Yealink SIP-T46G - Page 388

Appendix
375
The call flow scenario is as follows:
1. User A calls User B.
2. User B is busy on the IP phone and unable or unwilling to take another call.
The call cannot be set up successfully.
User A Proxy Server User B
F1. INVITE B
F2. INVITE B
F3. 100 Trying
F4. 100 Trying
F5. 486 Busy Here
F6. 486 Busy Here
F7. ACK
F8. ACK