[Serusers] Proxy requests between domains

Hi all, I've got a question regarding proxying requests between domains, I hope someone can help me... Take for example two domains, reseller.com & gateway.com. A SUA hangs off of reseller.com and places a call to the PSTN. For it to go out via the PSTN reseller.com forwards it onto gateway.com. Is there some kind of check you can do in ser.cfg that would allow you to determin if the request came from the reseller.com proxy or directly from the SUA? I'd like to stop SUA's from directly placing calls out via gateway.com and forcing them to go via there own sip servers. Then using this method along with RADIUS authentication I think it should be possible to secure our gateways? One of my colleagues suggested writing a module that would compare the given uri against a username/IP/domain in a database....? Many Thanks, Alan ------------------------------------------------------------------------------------------------------- This email, and any files transmitted with it, is copyright and may contain confidential information. The contents are intended for the use of the addressee(s) only. Unauthorized use may be unlawful. If you receive this email by mistake, please advise sender immediately. The views of the author may not necessarily constitute the views of Telco Electronics Limited. Nothing in this mail shall bind Telco Electronics Limited in any contract or obligation. Telco Electronics Limited 6-8 Oxford Court Brackley Northants NN13 7XY Tel 07000 701999 Fax 07000 701777