Yealink SIP-T48G Administrator's Manual page 594

Administrator's Guide for SIP-T2_Series_T4_Series IP Phones
The following figure illustrates a successful call between Yealink SIP IP phones in which
two parties are in a call, one of the participants receives and answers an incoming call
from a third party. 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 A calls User B.
2. User B answers the call.
3. User C calls User B.
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