VOIP=INFOから

>>441
The outbound proxy is a normal SIP proxy.
You configure your client, the phone or software, to use the proxy for all SIP sessions,
just like when you configure your Web browser to use a Web proxy for all Web transactions.

https://www.voip-info.org/sip-outbound-proxy/


Proxies are also useful for enforcing policy (for example, making sure a user is allowed to make a call).
A proxy interprets, and, if necessary, rewrites specific parts of a request message before forwarding it.
A request may traverse several proxies on its way to a UAS.
Each will make routing decisions, modifying the request before forwarding it to the next element.

https://www.voip-info.org/sip-proxy