Bulk SMS App for iPhone on Schedule A friend who runs a spa wants to send out a reminder to all her customers four weeks after their last appointment. It is a small number, half a dozen per day. But I need an app that can send an sms to a group of customers that a separate program generates. (Separate program runs on a PC, phone is an iPhone.)

Does such a think exist?

I know I can use an SMS gateway for this, problem is that when the message goes out, the reply has to come back to HER phone number. So if the message says "Would you like to schedule an appointment", when the customer his reply they want to say "How about tomorrow at 12pm?" and that go to the spa onwer's phone. SMS gateways don't seem to be able to do that reliably. So I wanted to go through the phone directly.

Any other suggestions to achieve the same goal would be appreciated.
You'll have far better luck doing this on Android as opposed to iOS due to restrictions on sending SMS from applications is something that's not even kosher for App Store apps AFAIK.

There are SMS providers that allow voice and SMS from the numbers - you can check out Twilio for that. Also Google Voice offers SMS to email, so your business could switch to using that and use an email program to queue the SMS for bulk delivery as required.

Sorry to give you a no answer, but there just isn't a market for this sort of app to run natively on iOS.