[Serusers] Ser + Asterisk for VoIP service provider

Hello, I have recently been put in charge of starting up a VoIP project connecting voip trunk lines to business' existing PBX's. I have decided to go all open source and have figured out asterisk pretty well. The problem is with SER. There does not seem to be a lot of clear documentation on asterisk interoperability. My idea is to use SER for the bulk of the call routing and asterisk for voicemail, billing, and other apps. All calls will be sip to me and then passed onto a VoIP provider who will handle all Long distance and PSTN service. Does anyone have any suggestions on setup, or any config files they could email me please? Thanks