In a fast-changing world, it’s only human to cling to familiar symbols of stability and familiarity. But sometimes, change becomes inevitable and needs to be accepted.

Like it or not, prepare to say goodbye to the notion of telephone area codes linked to a specific county or geographic region and used only when dialing long-distance calls. Get ready to say hello to 10-digit dialing of all local calls, even to neighbors across the street.

Ten-digit dialing becomes mandatory today in Miami-Dade County, after four months of being optional. Within a few years, it will be extended across South Florida and the nation.

All phones in Miami-Dade and Monroe counties (the Florida Keys) previously had the 305 area code, and existing phone customers will be allowed to keep it. But after the few remaining unused 305 numbers are assigned, any new telephone numbers issued in Miami-Dade will have the 786 area code.

In addition, all local calls within Miami-Dade wll require people to dial either 305 or 786. Dialing a 1 or 0 first is not required to dial local calls.

In reality, 786 and 305 won’t even be “area codes” any more, covering identifiable geographic areas of South Florida, just three-digit phone number prefixes.

Major change may be an unwelcome disruption, but is necessary. BellSouth and other local phone service providers are running out of the 7.9 million available phone numbers using area code 305 because of an explosive growth of new phone numbers for fax machines, cell phones, computer modems, pagers, beepers, voice mail services and home and office phones. Broward County switched from 305 to the 954 area code in 1996, and Palm Beach County switched twice, first from 305 to 407 in 1988 and then to 561 in 1996.

For Miami-Dade, phone companies and the ** txt: End of column 1 **Florida Public Service Commission wisely resisted pressure to switch to a “geographic split” area code plan. That would have divided the county into two area codes at State Road 836 south of the Miami Airport. Both plans had pluses and minuses, and both would cause inconvenience, but the “overlay” plan to give the 786 prefix to new numbers is the more desirable option for the long-range.

It speeds an inevitable transition to 10-digit dialing on local calls everywhere. It avoids the cost and disruption of making anyone change their existing area code to a new one. It sets a precedent for the future, where a boom in Florida phone customers will require even more area codes, making multiple geographic splits too disruptive an option. And it mirrors what is already happening in other major metropolitan areas like Atlanta, New York, Chicago, Los Angeles and Houston.

The overlay plan’s biggest drawback is that next-desk employees in one company could have different phone prefixes. So could parents and children with separate home phone lines, next-door neighbors or people adding extra lines for computers and fax machines.

Before 1988, there were only three area codes in Florida. With the addition of 786, there will be 10. By 2012, state regulators expect the state to have 20.

If you live in Broward or Palm Beach counties, and are saying “sure glad it’s not happening to me,” don’t get too comfortable. Your turn to enter the “10-digit zone” will come – probably for Broward in December 2005 and for Palm Beach County in April 2006.