Yealink SIP-T52S Administrator's Guide

Administrator’s Guide for SIP-T2 Series/T19(P) E2/T4 Series/T5 Series/CP860/CP920 IP Phones
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with “Server Hello Done” message.
Step3: IP phone sends session key information (encrypted by server’s public key) in the “Client
Key Exchange” message.
Step4: Server sends “Change Cipher Spec” message to activate the negotiated options for all
future messages it will send.
IP phones can encrypt SIP with TLS, which is called SIPS. When TLS is enabled for an account,
the SIP message of this account will be encrypted, and a lock icon appears on the LCD screen
after the successful TLS negotiation.
Certificates
The IP phone can serve as a TLS client or a TLS server. The TLS requires the following security
certificates to perform the TLS handshake:
 Trusted Certificate: When the IP phone requests a TLS connection with a server, the IP
phone should verify the certificate sent by the server to decide whether it is trusted based
on the trusted certificates list. The IP phone has 76 built-in trusted certificates You can
upload 10 custom certificates at most. The format of the trusted certificate files must be
*.pem,*.cer,*.crt and *.der and the maximum file size is 5MB. For more information on 76
trusted certificates, refer to Appendix C: Trusted Certificates on page 1012.
 Server Certificate: When clients request a TLS connection with the IP phone, the IP phone
sends the server certificate to the clients for authentication. The IP phone has two types of
built-in server certificates: a unique server certificate and a generic server certificate. You
can only upload one server certificate to the IP phone. The old server certificate will be
overridden by the new one. The format of the server certificate files must be *.pem and
*.cer and the maximum file size is 5MB.
- A unique server certificate: It is unique to an IP phone (based on the MAC address) and
issued by the Yealink Certificate Authority (CA).
- A generic server certificate: It issued by the Yealink Certificate Authority (CA). Only if no
unique certificate exists, the IP phone may send a generic certificate for authentication.
The IP phone can authenticate the server certificate based on the trusted certificates list. The
trusted certificates list and the server certificates list contain the default and custom certificates.
You can specify the type of certificates the IP phone accepts: default certificates, custom
certificates or all certificates.
Common Name Validation feature enables the IP phone to mandatorily validate the common
name of the certificate sent by the connecting server. And Security verification rules are
compliant with RFC 2818.
Note
In TLS feature, we use the terms trusted and server certificate. These are also known as CA and
device certificates.
Resetting the IP phone to factory defaults will delete custom certificates by default. But this
feature is configurable by the parameter “static.phone_setting.reserve_certs_enable” using the
configuration files.

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