As someone that used to be more interested in this stuff, it seems I missed the part where SS7 access became generally available. The first I saw mention of it, I think, was on an SMS provider's web site under a "Contact Us" type banner. Which makes me wonder, what changed to allow more businesses access and more importantly where do I sign up? :)

SS7 is one of those revered buzzphrases from my teen years, even getting to play with it for a weekend would really sweeten my Christmas.