JAIN-SIP and 1 SipListener

After doing a huge Google search I think I've found my answer. There is 1 SipStack per IP. There is 1 SipListener per SipStack (for ALL SipProviders, not EACH SipProvider). So, for SipUnit to work, we need it to listen on 127.0.0.1 and the module to run on the external address.

I don't know why JAIN-SIP was architected this way but it makes me feel uneasy.