Global GSM subscriber growth is expected to slow from a year-on-year rate of more than 22 percent in 2006-07 to 14 percent in 2008-09.

That forecast, from ABI Research's Mobile Subscriber Market Data report, is mainly due to the increased migration of subscribers to UMTS 3G technologies.

"Within the GSM subscriber population, EDGE is expected to maintain a high growth rate following increased deployments in all emerging markets," said Jake Saunders, vice president of Asia-Pacific for ABI, in a statement.

"Nonetheless, GSM, including EGGE and GPRS, is still expected to have the highest number of subscribers of all mobile technologies, with a 70 percent global market share in 2013, dropping from 78 percent in 2007," he said.

According to the market researcher, UMTS, including HSDPA, saw an estimated 83 percent year-on-year growth rate in 2006-07.

ABI said global GSM subscriber numbers will record a negative growth rate starting in 2013. That's because GSM by then will become less attractive compared with the cheaper 3G services.

The company also expects losses due to the proliferation of mobile WiMax and 4G networks.

On the other hand, the W-CDMA -- including HSDPA and HSPA -- global market share is anticipated to rise from slightly less than 5 percent in 2007 to about 14 percent in 2013.

However, the CDMAone and iDEN subscriber bases have been declining in the last five years. ABI said that by 2010, most subscribers to these technologies will have migrated to either GSM or CDMA2000 networks.

CDMA2000, including EVDO, has not grown as much as UMTS.

"CDMA2000's growth rate is expected to decline, particularly with the increased talk of CDMA2000 operators adopting LTE in their 4G roadmaps," said ABI research analyst Hwai Lin Khor in a statement.

"However, ABI Research expects that CDMA2000 technologies, particularly the 450MHz implementation, will remain attractive for rural coverage due to their wider network range," he said.