I'm guesstimating you'll find an upper bound, assuming "friendly" telcos that don't start rate limiting, or dropping SMSs, at no more than about 6kbps. Quite likely less.
GSM data (which is normally possible anywhere where you can get a GSM voice connection) is 9600bps and uses the full, raw GSM data/voice channel. You'd not be able to exceed the channel bandwidth. Then you have the SMS overhead. And you're unlikely to manage to max out the channel.
I'm guesstimating you'll find an upper bound, assuming "friendly" telcos that don't start rate limiting, or dropping SMSs, at no more than about 6kbps. Quite likely less.
GSM data (which is normally possible anywhere where you can get a GSM voice connection) is 9600bps and uses the full, raw GSM data/voice channel. You'd not be able to exceed the channel bandwidth. Then you have the SMS overhead. And you're unlikely to manage to max out the channel.