Yealink T27P Administrator's Guide

Configuring Security Features
503
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 responding 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
SRTP is configurable on a per-line basis. When SRTP is enabled on both IP phones, RTP
streams will be encrypted, and a lock icon appears on the LCD screen of each IP phone
after successful negotiation.
Note
If you enable SRTP, then you should also enable TLS. This ensures the security of SRTP
encryption. For more information on TLS, refer to Transport Layer Security on page 493.

Yealink T27P Specifications

General

Wall Mountable	Yes
Local Phonebook	1000 entries
Bluetooth	No
Wi-Fi	No
Gigabit Ethernet	No
Display	3.66" 240x120 pixel graphical LCD with backlight
Audio Features	HD voice, Full-duplex speakerphone
Network	Dual-port 10/100 Ethernet switch
Protocols	SIP v1 (RFC2543), v2 (RFC3261)
Power	IEEE 802.3af PoE
Connectivity	2 x RJ45 10/100M Ethernet ports
Voice Codecs	G.711(A/μ), G.722, G.723, G.729AB, G.726
EHS	Supports EHS with Plantronics headsets
Headset Port	Yes
Power Adapter	5V DC (optional)