Yealink CP860 [382/417] Unsuccessful call setup called user does not answer

Administrator’s Guide for CP860 IP conference phones

370

The following figure illustrates the scenario of an unsuccessful call caused by the called

user’s no answering. In this scenario, the two end users are User A and User B. User A

and User B are located at 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

Step

Action

Description

INVITE—User A to Proxy

Server

User A sends an INVITE message to a

proxy server. The INVITE request is an

invitation to User B to participate in a

call session.

In the INVITE request:

 The IP address of User B is inserted

in the Request-URI field.

 User A is identified as the call

session initiator in the From field.

 A unique numeric identifier is

assigned to the call and is inserted

in the Call-ID field.