But a recent chilly spring morning found Beyer breakfasting with several other Chicago executives and giving full attention as a telephone consultant explained in exquisite detail that next January much of Alabama will answer to the area code 334. And soon thereafter, parts of Washington state will get 360, and Arizona will welcome 520.

Beyer focused on this technologic minutiae because it's such a radical change in North America's numbering system that every business in the country with its own phone-switching system must upgrade its equipment to accommodate the new numbers.

For the first time, the middle digits in area codes won't have to be either zero or one. It's a change that multiplies available phone numbers fivefold, but it also makes area codes indistinguishable from local prefixes. And that requires more sophisticated switches to cope with the new numbers.