BT will this week attempt to kick-start its reentry into the mobile market when it unveils a Blackberry-style device that lets you send and receive e-mail and access the internet on the go.

It is striking back against mobile-phone operators such as Vodafone and 3, which each week are selling thousands of “don-gles” that plug into laptops.

BT is also seeking to guard against incursions by the likes of O2, once part of BT, which last week began a marketing campaign for its own fixed-line broadband offering. Mobile operators have also been experimenting with “femtocells” to set up 3G transmitters in the home.

The launch, on Wednesday, is thought to be based on a gadget from the Asian manufacturer HTC. It will switch from BT’s wireless Home Hub indoors to Vodafone’s network on the move and is expected to be sold with its broadband package.

BT hopes this new push will have a bigger impact than Fusion, a hybrid home and mobile-phone service that operates in a similar way. It amassed only 45,000 customers in three years, with most inroads made in the corporate marketplace.

“The thing I regret most with Fusion is that no-one else came to market in the UK,” said BT’s new chief executive, Ian Livingston. “That was one of the most difficult things. It made it very difficult for us to explain the proposition.”

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