With the NEC that I had to flipflop, I made *(star) the first digit of internal extensions.

So to dial 1(234)567-8901 sent you outbound, but *1234 gave you Joe's extension (which would have been 1234).

The big issue came up in blocking xxx-555-1212 (customer request)and xxx-976-xxxx numbers. That PBX could not handle conflict dialing. Also, it had a "six-digit" feature in ARS (look at the 6th digit, i.e. CO prefix) but since we didn't have a leading 9, that made CO prefixes the fifth digit, not the sixth. It had the ARS table from hell by the time we were done.

We cursed the salesmen soundly for making us do that.

Hope that helps.