Yealink SIP-T31G Administrator's Guide

Security Features
114
When you place a call on the enabled SRTP phone, the phone sends an INVITE message with the RTP/RTCP
encryption algorithm to the destination phone. As described in RFC 3711, RTP/RTCP streams may be encrypted
using an AES (Advanced Encryption Standard) algorithm.
Example of the RTP encryption algorithm carried in the SDP of the INVITE message:
m=audio 11780 RTP/SAVP 0 8 18 9 101
a=crypto:1 AES_CM_128_HMAC_SHA1_80 > inline:NzFlNTUwZDk2OGVlOTc3YzNkYTkwZWVkMTM1YWFj
a=crypto:2 AES_CM_128_HMAC_SHA1_32 > inline:NzkyM2FjNzQ2ZDgxYjg0MzQwMGVmMGUxMzdmNWFm
a=crypto:3 F8_128_HMAC_SHA1_80 inline:NDliMWIzZGE1ZTAwZjA5ZGFhNjQ5YmEANTMzYzA0
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:18 G729/8000
a=fmtp:18 annexb=no
a=rtpmap:9 G722/8000
a=fmtp:101 0-15
a=rtpmap:101 telephone-event/8000
a=ptime:20
a=sendrecv
The callee receives the INVITE message with the RTP encryption algorithm and then answers the call by respond-
ing with a 200 OK message which carries the negotiated RTP encryption algorithm.
Example of the RTP encryption algorithm carried in the SDP of the 200 OK message:
m=audio 11780 RTP/SAVP 0 101
a=rtpmap:0 PCMU/8000
a=rtpmap:101 telephone-event/8000
a=crypto:1 AES_CM_128_HMAC_SHA1_80 inline:NGY4OGViMDYzZjQzYTNiOTNkOWRiYzRlMjM0Yzcz
a=sendrecv
a=ptime:20
a=fmtp:101 0-15
When SRTP is enabled on both phones, RTP streams will be encrypted, and a lock icon appears on the LCD
screen of each IP phone after a successful negotiation.
Note: If you enable SRTP, then you should also enable TLS. This ensures the security of SRTP encryption. For more inform-
ation on TLS, refer to Transport Layer Security (TLS). You can configure the IP phone to include unencrypted RTP/RTCP
streams in SDP offers by “account.X.srtp.unencrypted_rtp.enable”/”account.X.srtp.unencrypted_rtcp.enable”.
Topic
SRTP Configuration
SRTP Configuration
The following table lists the parameters you can use to configure the SRTP.
Parameter
account.X.srtp_encryption
[1]
<MAC>.cfg

Yealink SIP-T31G Specifications

General

Mounting kit	Yes
Number of handles included	1 pc(s)
Display diagonal	2.3 \
Display resolution	132 x 64 pixels
Operating temperature (T-T)	-10 - 50 °C
Operating relative humidity (H-H)	10 - 95 %
Voice codecs	G.722, G.729, AGC, G.729A, AJB, PLC, G.711Mu, VAD, G.711a, G.723.1, G.726, iLBC, CNG, OPUS
AC adapter input voltage	100 - 240 V
AC adapter output current	0.6 A
AC adapter output voltage	5 V
Power consumption (typical)	3 W
Lines quantity	2 lines
Phonebook capacity	1000 entries
Number of VoIP accounts	2
Sustainability certificates	RoHS, REACH
Networking standards	IEEE 802.3af, IEEE 802.1p, IEEE 802.1Q, IEEE 802.1x
Ethernet LAN data rates	10, 100, 1000 Mbit/s
Ethernet LAN interface type	Gigabit Ethernet
Mounting	Desk/Wall
Handset type	Wired handset
Product type	IP Phone
Product color	Gray
Harmonized System (HS) code	85171800

Weight and Dimensions

Depth	189 mm
Width	188 mm
Height	162 mm
Package depth	210 mm
Package width	213 mm
Package height	103 mm