Until 1993, all of southeastern and east central PA, including Philly and the Lehigh Valley, was 215 country. Then around 1998 the phone company started running out of 215s. So, the Valley got its own code - 610. Not too long after, cell phones became popular, and the advent of the 484/610 overlay area began. 484 and 610 cover the exact same geographic area, but... 610 numbers are scarce, so most newcomers get a number with 484.
484? What kind of an area code is that?
That's what a lot of locals thought, and they've fought tooth and nail to keep their 610 numbers and get a 610 area code for their cell phone number, too. Area codes can be a status symbol. And for Lehigh Valley natives, 610 means: I've been here a while. Nothing is so quick to distinguish a newcomer, than filling out a form and entering 484 in the home phone field.
This came up recently when an acquaintance was selecting a contractor to do work in her home. 610 means this guy's been in business for a while, she reasoned. 484... you never know about those people.
Natives, pray tell: have you held tight to your 610 number? Newcomers, had you even thought of this?