Yealink SIP-T2 SERIES Administrator's Manual page 884

Administrator's Guide for SIP-T2 Series/T19(P) E2/T4 Series/CP860 IP Phones
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
Procedure
SRTP can be configured using the configuration files or locally.
Configuration File
Local
862
Transport Layer Security
<MAC>.cfg
Web User Interface
on page 850.
Configure SRTP feature on a
per-line basis.
Parameter:
account.X.srtp_encryption
Configure SRTP feature for IP
call.
Parameter:
account.17.srtp_encryption
Configure SRTP feature on a
per-line basis.
Navigate to:
For
SIP-T48G/T46G/T42G/T41P/T40P/
T29G/T27P/T23P/T23G/T21(P)
E2/T19(P) E2/CP860:
http://<phoneIPAddress>/servl