[intrasight]

When I did programmatic SMS for a project ~10 years ago, I just used SMTP and the email equivalent of the SMS address. I haven't done similar projects since then, so I'm curious if there is some reason that approach would no longer work.

[headcanon]

In addition to having to know the carrier, the text message itself sometimes includes email-style metadata (like FROM, SUBJECT, MESSAGE, etc) that varies by carrier, so its difficult to control the experience. Its one of those things thats good for a personal project but not for a service that sends lots of text messages to users.

I didn't know this until I just tried it, but doing it over email supports replies (at least on AT&T), which is pretty cool.

[intrasight]

In the app I had built (for NBA) I think we just asked people for their carrier name. Or we may have used a lookup service - I don't recall.

[zackbloom]

That only works if you know the carrier (as every carrier has a different email address), and I imagine it doesn't work internationally.

[cybrjoe]

Another problem is throttling and support. If you end up on the bad side of their spam filter it's tough to convince them to unblock you. They all have API's now that you can pay for access to, so they try and push you that route.

[Twirrim]

Many telcos throttle limit that route. I know of one company who used that method for sending texts from alarming to their oncalls. When they had a major incident and lots of pages went out, AT&T ended up blocking them from sending messages that way for a few hours, and they got warnings from the other major ones.