At 6 cents/SMS, I find Twilio and similar services way too expensive. Compare that to the unlimited SMS plan that I can get for 2€/month here in France, and setting up a gateway like that becomes very attractive.
In my experience it's very unstable however. Sending and receiving SMS can take anywhere from 5 to 30 seconds, and the modem can't do both at the same time. I tried configuring gammu's timeouts, loop delays and whatnot, but couldn't get something that's reliable enough for production.
Free's €2 per month is probably one of the best mobile deal in the world :). Beware though, last I checked using their SIM card in something not a mobile phone was against Fred's ToS. I don't know if it have since changed.
In my experience it's very unstable however. Sending and receiving SMS can take anywhere from 5 to 30 seconds, and the modem can't do both at the same time. I tried configuring gammu's timeouts, loop delays and whatnot, but couldn't get something that's reliable enough for production.