It's not going to be easy and it will be more inconvenient. After April 1, Islanders wishing to telephone anyone, anywhere on the Island will need to use the 508 area code.

This isn't an April Fool's joke. This is serious business. "Geography is really irrelevant here," said Bob Noble, a spokesman for Verizon, the telephone company. Everyone in southeastern Massachusetts from Nantucket to Rockport, from Boston almost all the way to the Berkshires will be required to dial the area code with their local number. It is part of a nationwide directive to shift to 10-digit numbers.

A resident of Aquinnah wanting to call town hall will have to dial 508-645-2300, no matter where they are in town, even if they call from next door at the fire station.

There is an easy explanation, though hard to rationalize on an Island. Mr. Noble said there are just not enough telephone numbers available and communities are going to get additional area codes. On Martha's Vineyard there will be a new area code added to 508. In the months, perhaps weeks ahead, it is very likely that a new telephone subscriber will get a new number and a new area code; that area code is 774.

In the past, when the telephone company ran out of numbers, they instituted a new area code for a region, or they initiated a new exchange. Martha's Vineyard has 627, 693, 696, 939 and 645.

"You might have had to split Martha's Vineyard into two area codes," Mr. Noble said. One end of the Island would be one area code, the other end would be another. Now there are going to be overlays. Your next door neighbor might have a different area code. "There are advantages down the road," Mr. Noble said. "You don't have to slice and dice smaller area codes."

Now your phone number has as many digits as your social security number. This is being heralded as a significant step in the modernization of the phone system, for it brings uniformity across the country and more phone numbers into the future without changing the number of those who already have a phone. According to a release issued by Verizon earlier this month: "Starting April 2, eastern Massachusetts will have four additional area codes with the same geographic boundaries as the current 617, 508, 781 and 978 area codes. These overlay area codes will eliminate the need to split the existing codes into ever smaller areas to create new phone numbers and will allow existing customers to keep their current phone numbers.

"The new area codes will coincide with existing area codes as follows: 857 will overlay 617; 774 will overlay 508; 339 will overlay 781 and 351 will overlay 978," the release said.

The release also stated: "Nationwide, the number of new area codes also is increasing as a result of the heavy demand for additional phone numbers."

Fortunately, a call for help, 911, remains unchanged.

Verizon personnel are stepping up their efforts to educate the public. They've set up an information toll free hot line at 877-554-3685; don't forget to use the area code. There is even a web site: http://www.verizon.com/support/areacode.html.

Mr. Noble said anyone with a computer or any telephone device should review and update the preprogrammed numbers to include area codes. The change impacts the use of cellular telephones and computer dial-up networks, pagers and security systems; anything that makes an automated call.

Mr. Noble said getting used to the change will take time. He recommends dialers consider using the area code now, just to be ready when it takes effect on April 2. Locally, it is not necessary to dial 1 before the area code, though doing it won't make a difference.

Mr. Noble said: "You've been able to dial the area code for local calls since September."