Comment by madhurjain

To add to this, If you want to send fast worldwide SMS reliably and without much hassle, use twilio or plivo or other such web sms gateways. If you want to send SMS locally, for cheap and willing to hack your way around, give GoSMS a shot. Given the time a modem takes to send an SMS, with a single modem connected, the rate of sending SMS is low (~1 message / 5 second).