[Users] Error Handling with Parallel Forking

Hello gurus, I'm attempting to do some rather crazy parallel forking and have found a few issues I'm hoping to solve. I thought I'd solicit some advice from the experts. Some background: Each device registers with its own unique information. No two devices share the same credentials. Since a random user might want their number sent to multiple phones, and maybe even a cell phone, I've done the following: if(method=="INVITE" && !isflagset(5)) { if(avp_db_load("$ru/username","fork")) { t_on_branch("1"); avp_pushto("$ru/username","$avp(s:fork)/g"); }; }; Then the branch route looks like: branch_route[1] { setflag(5); route(3); } The idea here is the fork avp contains one or more possible destinations, but we don't store a complete URI here. The branch route sends us back through the normal routing logic to lookup local users on the system, and maybe route something to an external PSTN gateway, or another proxy. The problem: I haven't found a way to gracefully handle the event when one of the possible destinations is a device that hasn't registered. Say we allow the user to have a soft client, so we add the username to the list of fork avps. If the device isn't registered, I have 2 options: 1) Use a default route 2) Detect that I should know who this is, and error out Either way, an error is produced, but I don't see a good way of detecting if we should push the 404, or generate a 404 back to the client. The polite method would be: Are there other branches still going? If yes, just exit this branch If no, relay, or generate an error back to the client So my question is how to do this last part. Am I crazy for even thinking about doing this in OpenSER? BTW, I'm using v1.1.1 --Chris