Shares in Research In Motion fell more than 20 per cent Friday as analysts raised concerns about less revenue from the lucrative service fees charged by the company to use its secure network.

BMO Capital Markets analyst Tim Long said changes to the company's service revenue model, outlined Thursday, add more risk for RIM, which is preparing for the launch of its next generation of smartphones and operating system next month.

"We have long viewed the recurring service revenues as the key value driver for the stock," Long wrote in a note to clients.

"With subscribers declining, and the potential for a faster drop in average revenue per user, service revenues could fall even faster. That said, the stock will be most dependent on the launch on new BB10 devices, and we believe it is too early to make a call on, success or failure."

The stock was down $2.92, or 20.93 per cent, at $11.30 late day Friday on the Toronto Stock Exchange on very heavy volume of more than 13.8 million shares, making it easily the most active issue on the TSX.

The drop in the stock came despite better than expected financial results by the company in its report after the close of markets on Thursday.

However, it was the plan for the service fees that attracted the most attention.

RIM (TSX:RIM) wants to launch an a la carte menu of services where both enterprise customers and casual smartphone users can pick their packages.

"The company had previously alluded to potential changes, but the issue is moving more to the forefront now," Long wrote in his report.

"We found the details lacking for such a significant announcement. We believe the service model for the consumer segment is more at risk than for enterprise."

RIM reported Thursday a third-quarter profit of $9 million, or two cents per share on $2.73 billion in revenue, compared with a profit of $265 million or 51 cents per share on $5.17 billion in revenue a year ago.

On an adjusted basis for the quarter, RIM said it lost $114 million or 22 cents per diluted share, coming in notably better than analyst expectations of a quarterly loss of 32 cents per adjusted share on revenue of $2.6 billion.