Adding a maddr Parameter to a URI

When you configure a SIP interface, you can configure the contact mode. The contact mode sets the contact header routing mode, which determines how the contact address from a trusted network is formatted. You set the contact mode to add a maddr parameter equal to the SIP proxy to the URI in the Contact header. For example, the URI from the prior example (sip:192.168.200.17:5060) becomes sip:123-trusted-eolmhet2chbl3@172.16.0.15;maddr=172.16.0.12.

Note:

For SIP elements that do not support the maddr parameter, configure a Contact mode as none.

You might require this encryption to cause other SIP elements in the untrusted network to send requests directly to the SIP proxy. Otherwise, the requests are sent to the home address. However, responses sent by the SIP proxy will have the SIP proxy’s source address, rather than the home address. Some SIP elements might drop responses that come from a IP address different from the one to which the request is sent.