SMS takes place on the control channel and not the data channel, which has a far more limited bandwidth. This means that SMS messages have to be queued up with control messages, and that a flood of SMS messages can disrupt all cell service in a region. What a stupid design.

And how about that price collusion, eh? They've gone up by a factor of 2 in a year for no reason at all related to either CAPEX or OPEX...