We are not "disseminating unwanted messages". A lot of what we're doing (e.g. customer support or missed call text back) would be things that users would already be doing conversationally over iMessage.

You can't guarantee one of your customers isn't going to do that dissemination though, right? No spammer is going to sign up saying "I'm a spammer that just got banned from <other service>! Can you guys help?"

Are you "conducting commercial activities"?

Getting a spam message about an abandoned shopping cart item is clearly "commercial activities" to me.