Cellular carrier Alltel this week began offering a free mobile shopping service on BlackBerry smartphones, allowing users to access products from retailers like Barnes & Noble, Best Buy, and Godiva Chocolatier.

Using the new Digby service, BlackBerry users with an Alltel subscription get access to a catalog of books, music, electronics, gifts, and other products. The service includes a "friendly interface" where subscribers can browse through these products, according to Alltel.

Alltel already has several retailers on board, such as Barnes & Noble, Best Buy, Drugstore.com, Godiva, FTD.com, Fossil, Quickgifts.com, Red Envelope, Vermont Teddy Bears, and Wine.com. Other retailers will be added weekly, the company said.

Digby offers the ability to put products in a shopping cart and group products from different retailers into one order, and the ability to complete a transaction on a BlackBerry. Alltel said the transactions are secured and password-protected.

Additionally, the service provides integration with calendars on BlackBerrys for reminders during special events.

Digby, however, is not restricted only to Alltel subscribers. According to the mobile commerce provider that created the service, it can be downloaded for free by anyone with a BlackBerry smartphone. The download is available on the Digby Web site.

Alltel is not the first carrier to offer a shopping service to mobile phone users. Verizon Wireless in October teamed up with mShopper, a mobile commerce infrastructure provider, to launch a mobile shopping application as part of the carrier's Mobile Web 2.0 service. With mShopper, Verizon Wireless subscribers can browse through 9.2 million products from hundreds of online retailers. By adding Mobile Web 2.0 to their mobile phones for $5 a month, subscribers can begin using mShopper, said Verizon Wireless.

Sprint took a slightly different approach, but is also one of the carriers that sees a bright future in mobile e-commerce. Sprint and GPShopper, a mobile marketing technology company focused on retail shopping, launched a mobile local product search application earlier this year. The application, called Sifter, lets users search products by keyword, product name, model number, or UPC code. It then uses a mobile phone's GPS technology to locate nearby retailers that sell the products. The service costs $2 a month.