Yealink SIP-T19 E2 T4 Series, Administrator'S Manual

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Administrator’s Guide for SIP-T2 Series/T19(P) E2/T4 Series/T5 Series IP Phones
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Step Action Description
F13 200OK—User C to Proxy Server
User C sends a SIP 200 OK response to the
proxy server. The 200 OK response notifies
User A that the connection has been made.
F14 200OK—Proxy Server to User A
The proxy server forwards the SIP 200 OK
response to User A.
F15 ACK— User A to Proxy Server
User A sends a SIP ACK to the proxy server.
The ACK confirms that User A has received
the 200 OK response. The call session is
now active.
F16 ACK—Proxy Server to User C
The proxy server sends the ACK message to
User C.
No Answer Call Forward
The following figure illustrates successful call forwarding between Yealink SIP IP phones in which
User B has enabled no answer call forward. The incoming call is forwarded to User C when User
B does not answer the incoming call after a period of time. In this call flow scenario, the end
users are User A, User B, and User C. They are all using Yealink SIP IP phones, which are
connected via an IP network.
The call flow scenario is as follows:
1.
User B enables no answer call forward, and the destination number is User C.
2.
User A calls User B.
3.
User B does not answer the incoming call.
4.
User B forwards the incoming call to User C.
5.
User C answers the call.