So we have 7-digit dialing in place for NANP destinations. The implementation is really stupid-simple: if 7 digits are dialed, take the originating number's area code and tack it on to the front of the dialed number. I am pretty sure this is how most commercial ITSPs do it (as tested also on Vonage and Packet8). But for certain areas, this doesn't properly mimic the 7-digit dialing that people who still have a POTS circuit from their LEC are used to. Take ours for example: I'm in Moscow, ID (NPA 208). We sit smack-dab on the WA/ID state border. 8 miles to the west of us is Pullman, WA (NPA 509). Both cities have the same ILEC: Frontier (f/k/a Verizon f/k/a GTE). There has been an understanding here since (I think) the mid-80s that calls between Moscow and Pullman are and will remain local. But on top of that, if you dial a Pullman NXX from Moscow or a Moscow NXX from Pullman as 7-digits, the call is patched through even though the NPA is different and even though (in some cases) both NPAs have NXXes that overlap with each other (although the corresponding NXX in the same NPA as the caller would be considered a long-distance call in all cases I can think of). The ILEC phone switch still does the "right" thing. It's been this way for YEARS, and people here are used to it. Now say I wanted to implement something like that for our customers. I know what the special exceptions are for this local market, and could probably make it work on our switch. But I only know about them because I've lived here and know the drill as a result. And I don't know how common or not this kind of thing is in other areas where you might be on the geographical edge of one's NPA(s). So the question I have is, is there some kind of central resource/authority that I can go to in order to find out what the dialing rules are for a given rate center (mandatory 10-digits/7-digits only within your own NPA/7-digits for certain local NPA-NXX outside your own NPA)? ...or is the only way to know for sure to find out from the locals? -- Nathan