That only kind of works... Actually, once when we needed to deliver many messages, we tried to get 6 usb gsm dongles. Then we discovered that you can overload 1 gsm transmitter with 6 standard dongles - maybe the equipment was just weird in some way, but at some point messages simply started to be rejected. Another problem is the delay - you need ~4s to get an acknowledgement which seriously limits the throughput. Then there are other problems with mass-sending... there is one 8-bit counter, but I can't remember now for which functionality (either replies, or delivery confirmations), which killed the idea in the end (it was supposed to be mass-notification, so thousands of texts / hour).
Just find someone who provides smpp gateways and save yourself the pain...
Ok right. I wasnt really thinking of bulk mail. Gsm modems work fine though for less frequent usage like sending notifications when the motion alarm is triggered etc..
Twilio isn't really for bulk sending either, is it?
