Telecom giant BT will re-enter the UK's mobile phone market, after unveiling a range of 4G subscriptions.The group confirmed the new service will utilise its spectrum as well as a spectrum provided in partnership with EE, Britain's largest mobile network operator, which BT is in the process of taking over for £12.5bn.However, regulators are yet to approve the deal, which is opposed by some of BT's rivals.The FTSE 100 company said its cheapest offer was priced at £5 a month for existing BT broadband customers, while users choosing to subscribe to BT Mobile will be able to watch Premier League matches BT owns the right to on their devices via an app, even if they are not broadband customers."An entry tariff of £5 a month will grab headlines, but inclusive access to BT Sport and five million wi-fi hotspots offers important differentiation in a cut-throat field," analysts at CCS Insight were quoted as saying by the BBC."We expect initial low-key marketing to heat up as BT makes a broader assault on the bundled telecom market over the summer."The deals that BT has announced so far are all Sim-card only, which means handsets are not included in the tariff.Britain's biggest broadband provider was among the first companies to enter the mobile sector in 1980s, before spinning off its Cellnet business, which was subsequently acquired by Spanish group Telefonica after being rebranded O2.Sky, the UK's second biggest broadband provider, has also unveiled plans to offer a mobile phone service.BT shares were up 0.76% to 469.03p at 14:53 on Wednesday.