Victor,
What would you do with the LRN response once received? Is the use case where a user wants to dial 4165555555, and you want fs to bridge to 4160000001?
If this is the case, I think you have two approaches. You could maintain your current dialplan strategy and call a script from the dialplan (but not xml_curl) which performs your LRN lookup.
The better approach seems to be to replace your current 'manual' dialplan for this case with an xml_curl dialplan. This way FS will invoke your xml_curl server, tell you a user wants to dial 4165555555, then you can natively call your LRN service (pqrs/route), and respond with the set/bridge commands to connect to the appropriate endpoint (in this case 4160000001). You can leave everything else in your manual dialplan if you wish.
Ian.