The telecoms giant had hoped that media regulator Ofcom's decision to allow BT Vision to offer Sky's flagship sports channels would bolster its digital TV platform.
However, the service has attracted just 1% of Sky's 5m Sky Sports customers, while the BT Vision platform has only 520,000 subscribers compared to Sky's 10m.
According to The Daily Telegraph, BT spent £6.3m on an advertising campaign to promote the availability of Sky Sports 1 and Sky Sports 2 on BT Vision.
That works out at £126 for every Sky Sports customer signed up since it started offering the channels in August. Only 20,000 of those customers were also former Sky subscribers.
In the three months to the end of September, Virgin Media spent around £700,000 on marketing its Sky Sports channels, but managed to sign up around 100,000 subscribers.
BT charges only around £6.99 a month for access to Sky Sports, but that comes as part of a bundled package of communications services.
Ian Livingston, the BT chief executive, admitted that there was "lot more to do" with BT Vision, but stressed the firm's long-term commitment to the service.
"Around 10% of our BT Vision subscriber base is now taking our Sky Sports package," he told reporters.
"We think it is important to offer our customers a broad range of options. I have been very, very clear to the market all along that this is a multi-year thing."
Livingston said that BT has lots of other "exciting" plans to boost BT Vision, including 3D movies on demand and the phased launch of BBC iPlayer, starting next month.
In the three months to September 30, BT reported a 43% increase in pre-tax profits to £406m on adjusted revenue of £4.977bn, down 3% quarter-on-quarter.
The company also added 114,000 new broadband customers, while the number of households receiving speeds in excess of 20Mbps reached 1.6m.
"We have made significant progress in improving profitability and cash flow, enabling us to invest in building the foundations for revenue growth in 2012/13," said Livingston.
He added: "Our fibre roll out has passed three million premises and BT Infinity orders are now running at over 4,000 per week.
"BT Vision customers now stand at more than half a million, with more developments planned to enhance our offering. Our share of DSL broadband net additions was 45%, one of our highest shares ever."