Yealink SIP-T21 E2 Administrator's Guide

Administrator’s Guide for SIP-T2 Series/T19(P) E2/T4 Series/T5 Series/CP860/CP920 IP Phones
1062
SIP 5xx—Server Failure Responses
SIP 6xx—Global Failures Responses
For more information on SIP Responses, refer to SIP Responses on page 1058.
Successful Call Setup and Disconnect
The following figure illustrates the scenario of a successful call. 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 answers the call.
3. User B hangs up.
User A Proxy Server User B
F1. INVITE B
F2. INVITE B
F3. 100 Trying
F9. ACK
F10. ACK
F5. 180 Ringing
2-way RTP channel established
F8. 200 OK
F7. 200 OK
F6. 180 Ringing
F4. 100 Trying
F11. BYE
F12. BYE
F13. 200 OK
F14. 200 OK
Step
Action
Description
F1
INVITE—User A to Proxy Server
User A sends a SIP 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

Yealink SIP-T21 E2 Specifications

General

Brand	Yealink
Model	SIP-T21 E2
Category	IP Phone
Language	English