hey mj, shoretel dial plan more flexible than you might think. we use 4-digit numbers througout, using the last four digits of a DID number as the extension. we are close to needing to move to 5-digits because telcos are starting to have difficulty matching openings in our coordinated dial plan (former nortel house here, too). cross that bridge when we must, in no hurry.

instead of 40 or 50 (or now 76) separate PBXs tied together, we get to manage one big system. let's us get more done with just us two guys. we self-install the WAN, LANs, routers/switches/and ShoreTel system, only buy the hardware. good luck on your decision, let us know how it goes (or how it went).