Want to move your home number? Take it to the Web

Q. I want to transfer a phone number I've had for decades, but my new ISP says I can't port it over because it's in a different "rate zone." Any other way I can keep my home number?

A. The Federal Communications Commission's rules about phone-number portability only cover moves from one service--wireline, wireless or Voice over Internet Protocol--to another within "the same geographic area." Otherwise, an FCC explainer says, "you may not be able to take your number with you."

That doesn't mean you're out of luck, however. In this kind of situation, Internet-calling services can let you keep an existing home number and even phone--and pay much less to continue using it. And unlike porting a residential number to your wireless service, this doesn't require ditching a known set of cell-phone digits.

But first you have to see if a "VoIP" service can take your number at all. Most have simple forms on their sites where you can enter your digits, or just the area code and exchange, to see if they can handle the port.

Most of the time, this should work. I checked this reader's Rochester, N.Y.-area number at the sites of consumer VoIP providers Ooma, Vonage and Lingo, and all three said it would be no problem--but could take 10 business days to complete.

But you can't count on this happening, because companies like those must sign agreements with residential phone services to cover these out-of-area moves.

Vonage, perhaps the best-known among them, has deals that allow it to port numbers "for approximately 90 percent of U.S. population," carrier-operations vice president Ed Mulligan said in a message sent along by a publicist.

At Lingo, you should be in luck unless you live in four states. Explained Laura Ramsey, marketing director for its parent firm Primus Telecommunications Canada: "Virtually all numbers are portable nationwide except in Alaska, Hawaii, Iowa, and Maine, where we can only provide new numbers."

"We estimate that 98 percent of phone numbers port over to Ooma successfully," said product-development vice president Dennis Peng in forwarded comments. But the company does meet occasional resistance: "Some providers use the phone number as a leverage point to try and keep their customers."

With all of these services, three basic issues apply. One is the need for extra hardware: Although you don't need to call through a computer, you do need to plug your phone into a small adapter device that will also stop working during a power outage. Another is varying compatibility with home-security services.

And 911 is not as much of a sure thing as with landline service. If you don't register your current street address with the service, that information won't automatically be passed to the 911 operator. And in certain locations, calling 911 connects you a nationwide call center, where an operator will take your information and patch you through to a local center.

But in the bargain, your costs should decline dramatically. You can expect to pay $20 or so for unlimited calling, including such features as voicemail you can check from any computer.

But if you're only keeping the line to hang on to a number friends and family know, consider less generous plans with a cap on voice minutes (at Lingo and Vonage, they can halve your monthly costs) or fewer features (Ooma's basic version is free except for taxes, though you still must pay for the required hardware).

Tip: Port a landline number to Google Voice through a prepaid wireless phone.

For those of you thinking "what about Google Voice?": Google's service only lets you port over a wireless number. But if you're determined to have the convenience of taking calls to your landline number on your smartphone--or any device running one of Google's Hangouts apps -- you can make that happen with a two-step process.

As Google Voice veterans like ZDNet's David Gewirtz have explained in detail, the first move is to port your landline over to a prepaid cell-phone plan. Buy the cheapest phone and the fewest minutes possible; once the porting process is done, you can flip the number into Google Voice for the usual $20 fee.

From then on, you can link that number to your mobile number to answer calls to it on on the go. You can place calls from your old landline number using one of those programs too, although in Android you'll need to install a separate Hangouts Dialer program.

Rob Pegoraro is a tech writer based out of Washington, D.C. To submit a tech question, e-mail Rob at rob@robpegoraro.com. Follow him on Twitter at twitter.com/robpegoraro.