I have an iPhone 5 using iOS 7 on Verizon. About a month and a half ago, I have been experiencing increased data usage. Last month I blew through 90% of my 2GB data plan in 15 days. I usually only use 1.1GB. I noticed that when I turn off data and am connected to wifi, I do not get ANY iMessages (they are not resent at text messages either) or mms messages. Visual voicemail will not work either. I am also not getting some SMS messages. Has anyone experienced this issue? I guess one question I have: does VVM, MMS, and/or SMS ever use data (3G/LTE, not wifi) to transmit instead of traditional CDMA? I think its odd that, at times, I turn my data on and get a flood of text messages. Not iMessages, not MMS, but straight up SMS. I hope that SMS is not counted as data AND one text! That would be like charging me twice!