The following standards should be kept when manually registering SIP clients:
SIP Server: Please see this article
SIP Port: 4242
Registration Timeout/Expires: 10 Minutes
NAT Keep-Alive Type: OPTIONS
NAT Keep-Alive Frequency: 30 seconds
DNS Record Type: SRV (if your application supports it, otherwise A)
DNS Resolvers: 188.8.131.52 and 184.108.40.206
Note 1: The Opus codec is no longer supported by our infrastructure.
Note 2: uLaw is required for ATAs (fax lines) to function.