You could fairly easily set up a similar system based on plain old phone calls. Just have a lookup on who's on-call and have the system ring their phone. It'd b

You could fairly easily set up a similar system based on plain old phone calls. Just have a lookup on who's on-call and have the system ring their phone. It'd be a trivial 20 line script given access to the db that stores that info and a twilio account or equivalent.