Yealink SIP-T52S Administrator's Guide

Appendix
1087
The call flow scenario is as follows:
1. User B enables busy call forward, and the destination number is User C.
2. User A calls User B.
3. User B is busy.
4. User B forwards the incoming call to User C.
5. User C answers the call.
Call is established between User A and User C.
User A Proxy Server User B User C
F1. INVITE B
F2. INVITE B
F3. 180 Ringing
F8. ACK
F9. INVITE C
F10. INVITE C
F11. 180 Ringing
F12. 180 Ringing
F13. 200 OK
F14. 200 OK
F15. ACK
F16. ACK
F4. 180 Ringing
F5. 302 Move Temporarily
F6. ACK
F7. 302 Move Temporarily
2-way RTP channel established
Step
Action
Description
F1
INVITE—User A to Proxy Server
User A sends the 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

Yealink SIP-T52S Specifications

General

Touchscreen	-
Display diagonal	2.8 \
Backlight display	Yes
Display resolution	320 x 240 pixels
Lines quantity	16 lines
Phonebook capacity	1000 entries
Number of VoIP accounts	12
AC adapter input voltage	100 - 240 V
Bluetooth version	2.1+EDR
Security algorithms	802.1x RADIUS, HTTPS, MD5
Ethernet LAN interface type	Gigabit Ethernet
USB 2.0 ports quantity	1
Ethernet LAN (RJ-45) ports	2
Mounting	Desk/Wall
Handset type	Wired handset
Product type	IP Phone
Product color	Black
Voice codecs	G.722, G.723, G.723.1, G.726, OPUS, iLBC
Volume control	Digital
Operating temperature (T-T)	-10 - 40 °C
Operating relative humidity (H-H)	10 - 95 %
Cables included	LAN (RJ-45)
Number of handles included	1 pc(s)
Front camera	No
Operating system installed	Linux

Weight and Dimensions

Depth	212 mm
Width	211.6 mm
Height	166.8 mm