[Serusers] SER IP PBX for multiple clients

Hello, I'm still trying to learn more about SER. I've been using Asterisk to manage virtual PBX services for different companies by using multiple contexts within Asterisk. However, since I only use Asterisk with SIP UAs and to communicate with ITSPs, I don't have the need to have all the fancy features Asterisk offers, plus I have the additional advantage of having the built-in NAT support in SER. The question I have is if someone can point me to the right place where I can see some sample configs that do more or less the things I need or if someone would be willing to share some of those configs on the list. Basically, I need to have the ability to manage any number of virtual PBX services where each virtual entity can manage their own extension numbering, DIDs, outbound CLID. I would probably just continue using Asterisk for voicemail services since I get the feeling that SEMS is still "unstable" to go into production, even for voicemail services only (unless told otherwise). The idea is that even if two companies define two extensions 101 and two extensions 102, when each company calls ext 101 or 102 internally, the call will be maintained within that company and would not cross over to the other company. Also, having features like one main number (DID) that could ring in multiple extensions simultaneously (forking) and if no one answers, leave a message in the general mailbox, or that each extension could have, additionally, a DID so that they can be reached directly from the outside. Any help would be greatly appreciated. Thanks, Waldo