Yes, I know what you mean, I meant that these days it's rare to have one coverage (voice/sms or data) without the other. I thought the previous poster was bringing up the scenario of no home internet access as a detriment to the messaging-over-data option. But after rereading, I think he meant that going over his mobile data cap was the problem. Messaging barely uses any data at all, however. You'd be hard-pressed to reach 1MB via texting over data.
He did bring up an important point about overages; the eventual move to data from traditional SMS will have to be customer-friendly in explaining overage, maybe even explicitly making the texting portion free/not count toward data overage. Which is basically similar to the unlimited texting you mentioned, negligible marginal cost for the carrier.
Originally Posted by dan330
sms messages are sent over the same radio as your voice calls..
normal sms does not use data network bandwidth.