Among those users who use MIM, 61 percent use it on a daily basis, compared with 55 percent who use SMS daily and merely 12 percent who use e-mail on their mobile.

"Currently, mobile operators have profited heavily from SMS, and these findings present a real challenge for their businesses," according to Matthew Froggatt at TNS Global.

"Do they try and keep consumers focused on SMS to maintain their revenue base, or offer consumers more choice in messaging? With increasing Internet functionality on new mobile phones, and MIM's strong mass market appeal, operators may have no choice but to promote this feature more widely," Froggatt added, eMarketer reported.