Heya guys, wanted to ask few questions about sending sms (marketing) using gsm modems. I've got one 8 port gsm modem up & running, wrote a software runs smoothly sms are being sent, received etc etc. The problem im facing is that im using AT&T sim cards and today (it was the first sending done) they blocked the sim cards (account suspended). went to store they have no clue what happened but i assume its the bulk sending. Can anyone share any similar experience and/or provide a solution like using different carrier and which ones ? im talking for sending of about 20-40K per day strictly in USA.