SMS had the dubious distinction of being the most expensive way to send data outside of non-commercial satellite and exotic military technologies. I can remember fees of $.35 for 160 7-bit characters worth of data, using bandwidth that was otherwise just going to waste. Carriers got so greedy with SMS.

That comes to about $2.1 million per gigabyte. But it's also a bit of an unfair comparison since one user consumes far less bandwidth using SMS vs general data.