We’ve got a system that is considered “master” on a campus that has upstream trunks, previously multiple buildings just had extensions, but now a directive has come out that several of these buildings should operate their own pbx.
OK, no problems, all setup, working, they can make outbound calls by master-pbx being set as default outbound. so far all good.
Last night they came to us and want a band of inbound routes (previously they never took outside calls), this is something I’ve never done before with IAX, from the pretty much useless documentation I can find, its a mater of inbound routes on master-pbx to internal-pbx-trunk-1,2,3,4 etc. this worked on my 2 test numbers, but I’ll be damned if I’m going to sit there and type our several hundred 
MY question is, is there an easier way? I am thinking of setting inbound route and trying
DID: _61775531[8]xx to DEST trunk-bld2
DID: _61775531[9]xx to DEST trunk-bld3
I’ve only used the regex in CID before so not sure if it is even recognised in DID and before I try this and pixx a lot of people off if it doesn’t work and collapses the system, any thoughts on this approach from someone who HAS done this in practise (not only in their head/on paper)? any gotchyas I need to be aware of assuming it works, or is there an entirely different way?
please note, the actually numbers have been slightly changed to protect the guilty 
