Zee Tawasha is an unabashed Blackberry addict, constantly sending urgent e-mails to employees at 30 mobile phone stores he owns across California, Arizona and Nevada.

Until recently, he used his fingers to painstakingly type out messages on the wireless device's cramped keyboard.

But with a new service launched by his network provider Sprint Nextel Corp. on Friday, Tawasha can press a button and say the recipient's name and dictate a message of up to 20 words into his Blackberry's receiver.

Within about a minute, the full message appears on the screen and he can send it off with one keystroke.

The technology was developed by privately-held MobileVoiceControl Inc., one of a number of companies developing voice control systems as consumers increasingly use mobile devices to surf the Web, shop and download ring tones.

While handsets have long incorporated voice controls, the features have not yet been embraced by many consumers because of limited functionality and accuracy.

It really works, said Tawasha, who has been testing MobileVoiceControl's product for about three months. But he said that the new technology has its limitations: You have to learn to speak slowly and clearly.

The product has been available on Sprint Nextel since late last year, although the carrier only formally launched it to business customers on Friday.

Analysts said other mobile networks could begin rolling out next-generation voice control services before the end of the year, hoping the improved functionality will spur demand for high-speed data services.

International Business Machines Corp. and Nuance Communications Inc. , two developers of voice-control technology, said recently they are working with major wireless carriers on similar products, although they declined to give details.

Motorola Inc. has said it plans later this year to start selling a phone with local language voice commands.

Text is about the most difficult and awkward user interface for anything on the cell phone. The best way is to talk to the damn thing, says Roger Entner, an analyst with research firm Ovum.

U.S. carriers have spent billions of dollars beefing up their networks for high-speed data services, but are still waiting for the investments to pay off. Usage remains limited partly because it is tough to surf the Web using small screens and keyboards.

A Reuters reporter testing the MobileVoiceControl product on a Sprint Treo 700p smart phone found text responses were 100 percent accurate on 10 e-mails entered by voice, although it took the system an average of 53 seconds to generate each email, with response times ranging from 30 seconds to 2 minutes.

The $6 a month service offers about 15 voice command functions, including email, text messaging, calendar entries, address book searches, Google searches and weather reports.

It is now available on high-end Sprint and Nextel smart phones. The carrier plans to start rolling it out on conventional cellphones before the end of the year.

Charles Golvin, an analyst with Forrester Research, said it will take three to four years before mainstream mobile phone users embrace voice controls.

The technology has come a tremendously long way, but it's not 100 percent, he said earlier this week. I think people get frustrated.