The number of U.S. cell phone subscribers is expected to increase more than threefold over the next four years, contributing a significant amount of revenue that carriers derive from data services, a market research firm said Tuesday.

The number of subscribers is projected to reach 24 million by 2010 from about 7 million this year, International Data Corp. said.

Even though only 10 percent of all U.S. subscribers are expected to pay for mobile video and television content and services, they are expected to become significant contributors to the average revenue per user (ARPU) carriers derive from the data networks, IDC said. The adoption rate assumes carriers meet quality expectations and price the services appropriately.

"Broadband adoption of video/TV services is emerging as the cornerstone of growth in this market," IDC research manager Lewis Ward said in a statement.

Broadband video/TV services should increase from less than half of all data revenues last year to about 85 percent of the total in four years, IDC said. A consumer survey suggests that a mix of on-demand clips and live streaming content are the most appealing.