Change .SIP.Network.{i}.ProxyServerTransport, REF 15031
When setting the value of *.ProxyServerTransport, if the value is transport "TLS", then the corresponding SRTP object is enabled otherwise(i.e. transport "UDP", "TCP", or "SCTP"), the SRTP object is disabled.
If need, the related SRTP object can be enabled or disabled later via setting to *.VoIPProfile.{i}.RTP.SRTP.Enable.