Route 10 digit dialed numbers to 4 digit VoIP extensions

Question

If a branch office phone dials a 10 digit TN of a VoIP phone, instead of simply dialing the internal extension, is there any way to route that call over the WAN instead of sending the call off to the PSTN? We have 30+ locations for which we'd like to apply this concept to.
We are using a mixture of PSTN's and SIP trunks, MGCP gateways, and CUCM 7.1
Thanks,

Answer 1

Absolutely although the answer will differ depending on the intracies of your particular dial plan design. Here are two common approaches:
(Adapt) Create translation patterns for your DID ranges within the same partition that the off-net route patterns exist. The more-specific translation pattern will be matched, preventing the call from going off-net. In your example as you've described it:
Route Pattern: [2-9]XX[2-9]XXXXXX or 9.[2-9]XX[2-9]XXXXXX
Translation Pattern:
FROM: 608[2-9]XX.XXXX or 9.608[2-9]XX.XXXX (Take note of the period and the fact that the pattern is more explicit than your route pattern!)
TO: Digit Discard: PreDot; Use a CSS that has the internal DNs.
(Start Over) This, along with a long list of other dial plan shortcomings has been designed in the E.164-based dial plan introduced with CUCM 7.0; however, this essentially requires you to start over. There is no easy way to convert from the legacy model. The E.164 "act local, think global" mentality would inherently catch this.
Full disclosure: I am a big proponent of the E.164-based design and am unlikely to be entirely impartial here.