SRTP 
To protect voice communication from eavesdropping, the WP810 support SRTP for media traffic using AES 
128&256, AES 128 or only AES 256. It is recommended to use SRTP if it’s supported by the SIP server (Or 
the service provider). SRTP can be configured under Web GUI → Account X → Audio Settings. 
 
Figure 11 : SRTP Settings 
Selects SRTP mode to choose (“No”, “Enabled but not forced”, “Enabled and forced”, or “Optional”). 
Default is No. It uses SDP Security Description to exchange key.