BlackBerry has sold around one million of the new Z10 smartphones it hopes will restore the firm to the industry's top table.
The handset's performance is widely seen as being key to the company's fortunes after a difficult couple of years when the firm lost ground and customers to rivals including Apple and Samsung.
Today, the mobile giant, formerly known as Research in Motion, announced a return to profitability in the most recent quarter and posted earnings of £65m after recording a substantial loss in the same period last year.
But despite the one million units sold analysts say the fourth quarter results reveal a worrying trend for the Canadian firm – with figures showing BlackBerry has lost about three million subscribers in the past three months, a figure which now stands at 76 million.
Stuart Miles, founder of technology and gadget site Pocket-lint, says the shipping of one million Z10 handsets in three months was unlikely to be enough to ensure a turnaround for BlackBerry.
"The UK did not take to the Z10 as well as it has done to other devices out there," he says.
"The iPhone 5 took three days to sell a million and the Samsung S4 will probably take the same time."
He adds: "I think the more worrying thing is the fact that they have lost around 33,000 subscribers every day for the last three months.
"If that continues at the same rate, and obviously they are hoping it won't, they are losing what amounts to 12 million a year. That's five years and they're out. Unless they can change that exodus, there won't be anybody left to use the system, no matter how good it is."
The one million Z10 phones sold bettered analysts' expectations of about 915,000, following a challenging period in which the firm's market share fell from 41 per cent in 2007, when the first iPhone came out, to 4 per cent in the first quarter of last year.
In today's report, BlackBerry said it shipped around six million handsets in the three months to March 2.
But revenue has fallen by 36 per cent to £1.8bn in the past year, while in the fourth quarter the company recorded a 2 per cent dip, with revenue down by about £32.4m on the previous three months.
Blackberry president and chief executive Thorsten Heins says customers "love" the new device which was launched in January with the motto "redesigned, re-engineered, re-invented".
"We have implemented numerous changes at BlackBerry over the past year and those changes have resulted in the company returning to profitability in the fourth quarter," say Heins.
"With the launch of BlackBerry 10, we have introduced the newest and what we believe to be the most innovative mobile computing platform in the market today."
He said the company would remain focused on improving its profitability and efficiency while driving innovation in the next fiscal year.
"We have built an engine that is able to drive improved financial performance at lower volumes, which should allow us to generate additional benefits from higher volumes in the future," he adds.