SMS seems to be hit and miss at the moment, with Twillo and Clickatell as the only choices. Since Google Hangouts can be used for SMS, is there a way to use that service, assuming the other two don't measure up? Is there anyone working on this, with an extension in anything resembling usable shape? What would it take, if nothing exists, to create something that uses Hangouts?
I have never seen this coming up for discussion and suspect the answer to that part of your question is 'no'. In terms of 'where to start', it would be worth looking at the two extensions Clickatell and Twilio but i suspect you have already looked at them.