[Freeswitch-users] Newbie - point me in the right direction

Hi, I am a real newbie. I have been building Asterisk based applications for a couple of years now. I am looking at migrating these apps to FreeSwitch - eventually. I want to do this gradually - I need to keep things running in the meantime. I have two Asterisk boxes, A1 & A2, each running a separate telephony app. We have an external SIP service with DID's NNNNN200 -> NNNNN299. We want to direct the incoming SIP calls so that the DID's NNNNN200 -> NNNNN219 go to Asterisk server A1 and NNNNN220 -> NNNNN299 to Asterisk server A2. Yes we really just want the calls switched on the DID. I'm struggling to know where to start - can someone point me in the right direction? Regards, John