I built this for a museum installation:
I didn’t end up building out the SMS component all the way because they ended up not wanting to expose it via text message, but if I remember right it was more or less done. It was built to work with webforms, Twilio, and I also experimented with IFTTT:
The principle was that this is a small/stupid PHP app that runs on a server, and you can then use QLab script cues (using e.g. curl commands) to extract the information from that server and use in QLab.
There are “in” endpoints for sending stuff in, and “out” endpoints to query from QLab. I used a periodic poll to retrieve input from museum patrons and update text cues projected into the museum, but you could use it to trigger things too (although it would only be as quick as the poll frequency).
Might be an interesting reference point if nothing else.
-C