Hello folks I hope you all are doing well I’m trying to solve my problem about how to send Bulk SMS text message to customers in United States, I live out of United States and I have a VOIP GSM Gateways with SMPP protocol with four SIM cards port. According what I know I need to live in USA to connect my GSM modem with SIM card it belong to any USA Cell Phone Carriers like AT&T, Sprint, T-Mobile, Verizon, etc, etc. I have been checking a lot web sites like (Twilio, nexmo, CallRail, CallFire, etc, etc) for sending SMS campaigns, most of them are very expensive. I wonder if it is technically possible to connect my GSM modem with an Outbound SIP Trunking service Provider with SIM cards from USA Cell Phone Carriers for sending SMS text message. I will appreciate any suggestion or forum reference, I need to know if I can still use the GSM modem or should I discard all ideas about it. Thanks in advance for your help.