I'm considering making changes to our System Numbering Plan. We currently use three (3) digit dialing for Extensions, Service Codes, Trunks and Operators. We've grown over the years and "number blocks" are starting to become scattered. I also think I want to separate our locations on their own prefix/designator.

Code
####
||||+-Extension Digit 3
|||+-Extension Digit 2
||+-Extension Digit 1
|+-Location (Operator, Trunk or Extension)

Reason for change:
  • Years ago, a "block" of internal numbers represented a department. People and the number of extensions used by a department have grown since then!
    With the current 3 digit dialing, we still have more than enough numbers, but they are getting scattered and not as organized (OCD issue for some of us).
  • Currently all 200 extension numbers are direct dials for (###) ###-#2##. We need more direct dials, but the new block from phone company overlaps with another a block internal only extensions.
  • Put first digit as a designation for location or system.


My questions:
  • Is it possible to keep the 3 digit extension while also having a 4 digit extension? I think I would either assign a VE to each 4 digit extension or just forward the 3 digit extension to the 4 digit. Company culture is very conservative and not that responsive to change; which is why I'd like to try and keep the 3 digit dialing.
  • Any specific items that I need to watch out for or consider? I'm still in the discovery/planning phase.


-JA