411 and 611 still work here when calling from a landline for Directory Assistance and Repair. On a Verizon cell phone, 611 gives you their customer service.
I agree with your CO tech friend.
In Centrex, we reused the same 2 codes for dial dictation that had been used with the 701 PBX by having Bell point those codes to unpublished Centrex line numbers. We had to create different codes (without * or #) for other features because at the same hospital, we were still using many rotary multi-line phones. Call Forward Universal, for example, which was *74, could now be dialed as either *74 or 274. It didn't matter if there was a 274 NNX in Atlanta, because to reach that 274-xxxx you would dial 9 first (or, after about 1996, 9 + 10 digits). Since this was a larger Centrex group shared by Ga. Tech, you had to dial 5 digits instead of 4, but they were all 4-xxxx (for 404-894-xxxx) or 3-xxxx (for 404-853-xxxx) or 6-xxxx (for 404-206-xxxx); that's why 2 was chosen. As long as you don't create numbering conflicts, you can be as creative as you wish.
1=may have been the intial number of the 4-digit code used for dial dictation
2=* as an initial digit for feature codes
3= 404-853- Centrex numbers (3-2477 for example)
4= 404-894- Centrex numbers'
5= not used. Reserved for future expansion of Centrex, where only the 3rd digit of the NXX needed to be assigned as a 5--it could be 805 or 895 or 225, whatever was available at the time.
6= 404-206- Centrex numbers
7=not assigned
8= Old Long Distance State network at Courtland St. 8 + Area Code + 7D or, for state phones, 8 + a 3-digit NXX C.O. code which did not match the NXX Bell used (For example, to call the Governor's office from Savannah, you could dial 8+222-1776 rather than 9+1+404-656-1776.)
9= Calls to outside (+ 7 digits to 404 and +10 digits to 770 Atlanta Suburbs; later +10 required for all)
0= Attendant at Ga. Tech
In fact, when you program a PBX, you can set up shortcuts in dialing by creating your own dialing plan. We programmed a Nortel Option 11 so that when you dialed 5 + a number between 01 and 48 (522 for example), you reached one of the 48 State Patrol Posts, rather than having to dial 9 + 10 digits for local posts or 91+ 10 digits for long distance locations. Dialing 2xxx translated to 9-404-624-2xxx to reach nearby Centrex lines that weren't on the PBX. (Note that this resulted in *fewer*digits dialed, not more.)
While Nortel won't allow conflicting codes like 30 and 301, on Mitel, this is not a problem either.
Or, you can submit to the FCC and AT&T and require, from your PBX, 9 + NPA + NXX + xxxx= 11 digits for every local call or 12 digits for long distance calls, even to frequently called locations of your same organization.
It's also a good idea to program the switch to translate 911 to 9911. From a PBX, if dialing 9 gives you an outside line, then if not reprogrammed, it would send only " 11" to the CO.