[OpenSIPStack] Incoming requests handling in upper registration mode

[Andrew P. <and...@po...>]

Dear all,

I am trying to use OpenSBC in b2bua upper registration mode with 
PortaSIP softswitch. Registration and outgoing calls for UAs behind 
OpenSBC are OK, requests are forwarded through OpenSBC to PortaSIP. 
Contact header hijacking works like a charm. But when it comes to 
incoming calls or, say, NOTIFY from external application server, there 
is a trouble. Rules that govern distinguishing between local and remote 
domains do backfire: since incoming requests hit PortaSIP first, an IP 
in To header does not match the IP address of OpenSBC's listener 
interface. It contains the IP address of PortaSIP.
So OpenSBC first checks the IP in Request-URI, sees that it matches the 
IP address of OpenSBC's listener interface, then checks the To header, 
sees it does not match AND sends request back to PortaSIP. This leads to 
a routing loop.
Can I instruct OpenSBC to overwrite IP address in To header with an AOR 
it knows for the request target and then send it out? Or I am missing 
something? Thanks in advance.

-- 
Sincerely,
Andrew Pogrebennyk