Verizon Wireless and Sprint Nextel Corp. (S) are introducing a BlackBerry e-mail phone that's compatible with the cellular technology more common in other countries in addition to the standard used on their own U.S. networks.

One key difference between the Verizon and Sprint versions of the new BlackBerry 8830 is that Sprint's will be "unlocked," enabling customers who take the device abroad to buy wireless service in other countries through other carriers.

Verizon's 8830 is locked so that it can only be used overseas through Verizon's roaming service.

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The new phone is a variant of the 8800 line introduced in February by BlackBerry maker Research in Motion Ltd. (RIMM) through AT&T Inc. (T)

The list price is $400, but Verizon will be offering it starting next month for as little as $200 for customers who sign up for both voice and data service with a two-year commitment.

Sprint, which won't start selling its 8830 until July, didn't disclose pricing. A spokeswoman said it will be competitive with Verizon's device.

The BlackBerry is being rolled out by Verizon with an international data plan costing $20 per month for unlimited e-mail access in about 60 countries on top of the regular BlackBerry subscription fee of $45 to $50 a month. Occasional travelers can opt to pay as they go for their data usage.

The device also can be used as a phone in more than 150 countries at a cost of $1.29 or $2.49 per minute, depending on the market.

RIM developed the dual-mode capability to suit Verizon's and Sprint's circumstances.

Both companies use what some experts consider a superior wireless technology known as CDMA. But the vast majority of the world's cellular networks run on a standard called GSM.

As a result, where GSM-based carriers such as AT&T and T-Mobile USA can easily offer phones that work overseas, Verizon and Sprint haven't had many options for their customers who travel abroad.

Though a dual-mode phone is an obvious solution, the drawback is the cost of adding more complex components and the engineering challenge of jamming them into a handheld device without making it bulky.

RIM overcame the second hurdle, squeezing in the dual capabilities without increasing the 8800's size.

Verizon, meanwhile, appears to have addressed the cost problem by offering a steep discount — a point driven home by its decision to "lock" the device, preventing users from using it with a rival carrier's service abroad.

It's undisclosed how much RIM is charging Verizon for each device. But after the assorted discounts, Verizon's 8830 is being offered for $100 less than AT&T's GSM-only version.

In fact, the 8830 from Verizon and Sprint is also equipped with a speedier technology for wireless Internet access than AT&T's version.

Verizon said it locked the new BlackBerry as part of its emphasis on ensuring network quality for customers, this time outside the United States.

But that policy disables one of the most popular attributes of GSM phones, all of which feature a slot for a removable, postage-stamp sized card that stores a user's account information.

The ability to remove that card, called a SIM, enables a user to buy multiple GSM phones and use whichever one suits the occasion.

More importantly in this case, GSM also enables a traveler to use a single phone, but buy wireless service from different providers in different countries. Then, by slipping the appropriate SIM into the phone in a given country, the user can cut back on the steep international roaming fees charged by carriers.

Vodafone Group PLC (VOD), which owns 45 percent of Verizon Wireless, will be providing much of the overseas roaming service for Verizon's 8830.

So by locking the BlackBerry 8830 to only work with a Verizon SIM, those two companies will be sure to capture the revenue from any calls made with the device from another country.

[Verizon (VZ) owns the remaining 55 percent of Verizon Wireless.]