Can you use your cell number on more than one mobile phone?

By Bruce Meyerson – ASSOCIATED PRESS
Updated: 06/04/07 6:55 AM

Q: I know people who use different cell phones for different occasions, but with the same phone number, almost like you’d change clothes or jewelry. How does that work?

A: It’s not quite as easy as just throwing on a different sweater, but many cell phone companies enable you to use more than one handset with the same phone number. So a person can conceivably carry an e-mail device like BlackBerry during work hours, then switch to a slender flip phone at night.

The process varies, depending on the service provider, and there are a few minor limitations as to which handsets can be used interchangeably.

Most important to remember, though, is that each device you want to use needs to be part of your wireless company’s device lineup: a Sprint phone won’t work with a T-Mobile account, and so on. There are some ways to work around this obstacle, but the process won’t appeal to most consumers.

Among the nation’s biggest carriers, AT&T Inc., Verizon Wireless and T-Mobile USA all enable their subscribers to move a phone number from handset to handset. But at Sprint Nextel Corp., only older phones in Sprint’s handset lineup can be swapped in this fashion.

The process is identical for customers of AT&T and T-Mobile, both of which use the globally dominant GSM technology for their cellular networks and phones.

With GSM, a customer’s phone number and account information are stored on a SIM, a removable smart card about the size of a postage stamp that fits in a slot within the battery compartment.

The size of the card and the slot is identical on all GSM phones. So to use multiple phones, all a customer needs to do is remove the SIM from one phone and insert it into the back of another.

There are a few minor caveats, as the formatting of the SIM does vary slightly in some cases with higher-end phones such as a BlackBerry or a T-Mobile SideKick, which feature customized capabilities for e-mail and text messaging. If you take the SIM from a regular phone, for example, and insert it in a BlackBerry, you’d be able to make calls or access a mobile Web page, but you wouldn’t be able to use it for the BlackBerry e-mail service.

At Verizon Wireless, the process for switching phones is handled entirely online rather than on the phone itself. That’s because Verizon’s service is based on a technology called CDMA that doesn’t involve a SIM. Instead, a user’s phone number and account information is stored within the device’s internal circuitry.

To swap phones, a Verizon customer needs to register for online account access through the same portal that users can view or pay their monthly bills.

On that Web site, there’s an “Activate Phone” link, which asks you to input an 11-digit code called an ESN for the device you’d like to work with your phone number. The ESN, unique to each handset, can be found printed inside the battery compartment.

The user needs to wait 10 minutes for the switch to work its way through Verizon’s systems, then type in “.228” on the new phone and press send, which triggers an over-the-air activation for that handset. To switch the phone number back to the original handset or yet another, you’d go back to the Web and repeat the process. Verizon Wireless says that customers who like to swap handsets may want to subscribe to Back-Up Assistant, a service that moves their contacts from one device to another for $1.99 per month.

Sprint, which also uses CDMA technology, offers a similar Web-based process to Verizon’s, but again only with older phone models. Newer models equipped for Sprint’s Vision multimedia data services cannot be swapped online.

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