If they were using the regular data channel, and they charged the regular (even though they are inflated as is) data prices, this would be a non-issue.
It's like if the USPS decided to charge a buck for post cards because people liked them more, so the logical thing to do would be to just stick the post-card in an envelope, but then the USPS declared that illegal and outlawed post card sized envelopes.
I googled for UTMS 3G (the most usual here in europe), and they still use the FREE signal channel:
"On umts, sms is packet switched - bit rate will be 16k...... cos it is sent on signalling channel."
ref: http://www.wirelessforums.org/uk-telecom-mobile/anyone-know-...