Yealink SIP-T38G, Administrator'S Manual

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Appendix
347
The following figure illustrates the scenario of an unsuccessful call due to the reason of
the called user not answering the call. In this scenario, the two end users are User A and
User B. User A and User B are located at the Yealink SIP IP phones.
The call flow scenario is as follows:
1. User A calls User B.
2. User B does not answer the call.
3. User A hangs up.
The call cannot be set up successfully.
User A Proxy Server User B
F1. INVITE B
F2. INVITE B
F3. 180 Ringing
F4. 180 Ringing
F8. 200 OK
F7. 200 OK
F5. CANCEL
F6. CANCEL