The biggest problem is the fact that you need something to send sms from...
Option 1:This could be a plain mobile phone, problem: you need to have it connected to your phone. Even if you fix that, you'll need to find a way to make that mobile send the text you want. Beacuase every mobile is build different that's not do-able i think.
Option 2: Use an external SMS server... Like Patchou sets up his own sms server from where users can send their sms. But that costs alot of money, Patchou would need to earn that back by making you pay money for every sms you send
Option 3: Use some free webservice that allows you to send SMS for free... But site like that can dicide to stop their free services and when that happens Plus! sms wouldn't work anymore.
All with all it's just to hard to make this work right i think.
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