TTT makes an important point. You want the numbers to match your dial plan for your stations. This keeps things simple. Make the service providers do their work! If they tell you all they have is junk numbers, they can get more numbers from the FCC's number pooling project. That is one of the reasons for number portability, be the company an ILEC or a CLEC. You might plan ahead and get a few more numbers for future expansion.
Wink-start is the most popular type of signalling for DID trunks. Also make sure your system has a SOLID GROUND REFERENCE! Problems such as intermittent service can happen on DID trunks when they don't have one. Polarity is important, if you have any tip/ring reversals that will block traffic, hence no calls!
Other good information to get is the DID trunk group number or name (TGN) and the route index (RI). This is helpful when reporting trouble on DID service. And the correct trunk numbers or designations help too.
Hope this helps!
....JIM....
