Having acquired EE for £12.5bn communications giant BT is returning to the mobile market, offering unrivalled 4G SIM-only plans for BT Broadband customers from just £5 per month. Also see: Best SIM-only deals

All BT's mobile plans come with free access to BT Sport, which holds the viewing rights to exclusive Barclays Premier League football matches, plus unlimited access to BT Wi-Fi hotspots. On a 12-month SIM-only plan from BT you can also make use of parental controls, and switch freely between plans during your contract.

There are three tariffs to choose from, with the cheapest just £5 a month for BT Broadband customers (£10 for everyone else). This deal nets you 500MB of 4G data, unlimited texts and 200 minutes. Also see: Best cheap 4G phones 2015

A second plan is suited to more regular internet users, with BT charging £12 a month (£17 for everyone else) for 2GB of 4G data, unlimited texts and 500 minutes.

Finally, heavy internet users can grab a massive 20GB of 4G data, unlimited texts and unlimited minutes for £20 a month (£25 for everyone else). Also see: What is 4G? A complete guide to 4G

By comparison, Vodafone is offering a special deal on the same tariff (Red XXL), but even while it's reduced by £10 it's still £10 more expensive than BT's 20GB plan at £30 per month.

EE's highest 4G SIM-only plan offers 5GB of 4G data for £27.99 a month, O2 offers 8GB for £30 per month and Three offers unlimited everything from £27 per month. Even GiffGaff can't compete with BT, charging £18 per month for 5GB of 4G data, unlimited texts and 1,000 minutes.

John Petter, chief executive of BT Consumer, said: “Offering BT customers the UK’s best value 4G data deal is a great way to start our journey towards re-establishing ourselves as a major player in consumer mobile.

“Our customers are consuming increasing amounts of data and they want the best possible connection wherever they are. It’s our ambition to meet this demand by combining the power of our fixed fibre service with wi-fi and the convenience of mobile.”

All BT's plans are SIM-only and for 12 months. You can use your existing phone, or pick up a 4G phone from the BT Shop from £99. BT Mobile customers can also benefit from a £50 discount.

Any person living within a BT Broadband household can take advantage of the deal, and a customer can have up to five plans on one bill to cover the entire family.

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