Moodle in English

For this to work I think you'd need an SMS to email relay, forwarding messages to a dedicated address, and they'd have to include things like a discussion ID in the message. And have their mobile number stored in their moodle profile so a script that reads/parses these emails could establish which user ID it belongs to. But it's not a bad idea.

A cron-style activity that runs a few times a day maybe.