This was due to the 3 big US wireless carrier's colluding to form the Campaign Registry, which is trying to force any business users of SMS to pay a verification fee ($50 iirc) and monthly fees ($ to $$ per month) just so you can send SMS for business reasons, even if it's person to person traffic where your just replying to your clients that texted you.

Had the FCC implemented something like this the rules would be much more consistent and the fee structure would not be so exorbitant, but instead the big 3 have formed a cartel to attempt to control SMS messages in the USA.