B: this is my number
A: which is?
B: (tells A what the phone number is)
Until this, what surprised me most was how people in Atlanta assumed that you had a car. This had led to utterances like it's less than 20 minutes from here, which actually meant that you had to take one or more interstate highways -- the sprawl's closest approximation of as the crow flies -- and then drive (or cruise) along to a certain exit and then take a few turns to get to the location in question. To be fair to the sprawl, this assumption is not an ill-founded one, but I tended to respect people who directed you without this assumption (something as simple as If you took I-75N, it would take you about 20 minutes to get there made a big difference).
But now it was caller ID. In this new century dominated by cellphones and internet telephony, a POTS line might seem anachronistic, but is hardly surprising. So assuming that you had caller ID (which is not free and not part of basic service, although most consumers seem inclined to sign up for it either in order to suppress all those annoying telemarketing calls or because it seems like "just a few bucks more"). I also suspect that some people habituated to cellphones even forget that they might be calling a POTS line; they assume that it's another cellphone and cellphones have "free" caller ID. In any case, it's another assumption that I don't think is ill-founded, but there's clearly a better way of handling a request for a phone number. X can call me back at ###-###-#### isn't so hard, is it?