I'm looking to use some online SMS services, this is for a workshop and I just need to advise people stuff is ready for collection and it looks like my billing system can plug into a few different ones. I'd like to be able to have people reply if they want to some services allow you to have the reply go to a mobile and I'm thinking this would be cheaper (I don't need a virtual number so no additional cost) and easier to manage as the phone will make an obvious noise that can be checked without needing a PC and it can be handed easily between people - so no my personal mobile number isn't going to workout. I have a few of very old handsets hanging around, so I do not need anything but a sim that is cheap to keep active, it doesn't need to be or data capable.
….Any ideas? I'm thinking there must be plans as people get these sort of SMS only sims for security devices don't they?