Yealink SIP T46G Administrator's Manual page 212

2. Click Browse to select the certificate (*.pem or *.cer) from your local system.
3. Click Upload to upload the certificate.
The dialog box pops up to prompt ―Success: The Server Certificate has been
loaded! Rebooting, please wait...‖.
Secure Real-Time Transport Protocol (SRTP) provides means of encrypting the RTP
streams during VoIP phone calls to avoid interception and eavesdropping. The parties
participating in the call should enable the 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.
The example of the RTP encryption algorithm carried in the SDP of the INVITE message
for reference:
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
Configuring Security Features
199