Sending bulk sms??

Hi. anyone know how to do it? My usual methods no longer work..

ive heard about GSM modems or whatever. i found some on aliexpress. if i get an 8 port modem and prepaid sims, is sending 1 texts every 3 minutes per number a good enough throuput not to get banned?

These modems allow IMEI changing, however, sim cards can be banned also and it will get very expensive fast if each sim doesnt on average send at least 10000 messages. even thats pretty awful. any help?