BT's pre-tax profit rose 38% from £375m to £517m in its fiscal first quarter as 251,000 new customers were introduced to its broadband network.
The telecoms giant's results for the first quarter of fiscal year 2011-2012 showed overall sales fell 5% year-on-year to £4.8bn from £5bn in the first quarter of 2010. BT Global Services and BT Wholesale sales were down 5% in the period, with BT Retail sales falling 4%.
Some 251,000 new customers signed up to broadband services using BT's network over the period. A total of 141,000 (59%) of those net additions chose BT's retail broadband products over other ISPs.
Ian Livingston, chief executive at BT, said the Openreach network infrastructure division showed its strongest ever sales growth, rising 5% year-on-year from £1.2m to £1.3m.
The company also increased superfast broadband network roll out to five million premises, pushing its total customer base to 200,000.
Livingston said, "Our superfast broadband network has now passed over five million premises and the customer base has almost trebled in the last six months. BT Global Services is making further progress in high growth economies."
BT Infinity - the firm's highest-speed broadband product - increased customers by 71,000 while the BT Vision set-top box customer base reached over 600,000. The total number of Wi-Fi hotspots grew by more than 200,000 in the quarter bringing the total to over three million.
"We remain the UK's number one broadband retailer with a customer base of 5.8 million at 30 June 2011," said BT in its financial report.
The firm said payments to telecoms operators were down 14% due to lower mobile termination rates (MTR) and reduced transit and wholesale call volumes.
BT hopes growth in BT Retail and Openreach can help the company achieve its future financial targets.
"This year we expect continuing good performances in BT Retail and Openreach to offset weakness in BT Wholesale EBITDA and to make further progress towards delivering our financial, operational and growth goals," said the company.
In its previous fourth quarter results, BT's profit was up 97% to £495m compared with the same period the year before, but revenue fell 6% to £5.06bn.