nate:n4: 'approved carriers' = local service providers such as Bulletin, Run the Red, Fronde etc. Anything else is liable to be dodgy/spammy. Cheap=no guarantees in this case.
Sure this decision, which affects a lot of legitimate people as well, should've been communicated, maybe given warning so other arrangements could be made? I have a lot of clients who use Clickatell, mainly for sending notifications of events, and it seems now we'll have to change providers.
The big issue we have with local providers is cost. Having big setup fees, huge monthly fees for API access is fine if you are a big corporate, but for some of the smaller players, it just isn't economical. Some of the companies you've listed, the monthly access fees are criminal.
Would Telecom entertain the idea of providing a low cost interface for SMS to small businesses?
Sounds like a good idea to me. So you could wear the per message cost if the monthly access cost was zero (for example)? If so, sounds like a business opportunity for someone.