Matrix SPARSH VP710, User Manual, Page: 717 / 1046

Matrix SPARSH VP710 User Guide 709
SRTP
Secure Real-Time Transport Protocol (SRTP) encrypts the RTP streams during VoIP phone calls to avoid
interception and eavesdropping. The parties participating in the call must enable SRTP feature simultaneously.
When this feature is enabled on both phones, the type of encryption to utilize for the session is negotiated between
the IP phones. This negotiation process is compliant with RFC 4568.
When a user places a call on the enabled SRTP phone, the IP phone sends an INVITE message with the RTP
encryption algorithm to the destination phone.
Example of the RTP encryption algorithm carried in the SDP of the INVITE message:
m=audio 50020 RTP/AVP 118 9 0 8 18 101
a=rtpmap:118 opus/48000/2
a=fmtp:118 sprop-maxcapturerate=48000; maxaveragebitrate=40000;
a=rtpmap:9 G722/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:18 G729/8000
a=fmtp:18 annexb=no
a=ptime:20
a=sendrecv
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
a=crypto:1 AES_CM_128_HMAC_SHA1_80
inline:NWM5YmZkZDk5YjI1OTg2MDgwOTM5ZjIxNmJkNTY5
a=crypto:2 AES_CM_128_HMAC_SHA1_32
inline:N2M1NmMzZTI2MGFkZjY5YWYzMGE5MWViYTljNzg4
a=crypto:3 F8_128_HMAC_SHA1_80 inline:NjMxYmIzMDIxNGExM2JkYWQxZTMyODQ1MThkYzg0
m=video 50022 RTP/AVP 97 98 99 117