PROXY_DOMAINS is the list of domains for which the proxy will be "authoritative". This means for any requests received for URIs in these domains, including subdomains, the proxy will attempt to map the URI to a local, registered contact address using the location service SBB.
If no user has registered at that address, the proxy will respond with a
4xx error code.
If the request is for a domain that the proxy does not know about, it will attempt to forward the request using standard SIP routing rules.
The properties in
sip.properties are substituted into SBB deployment
descriptors when the example applications are built.