I need some hardware for multiple SIM cards SMS sending. Preferably 200 sim cards. I would use Linux and some development boards like Raspberry pi etc. I have used raspberry with a USB dongle. Please advice solutions for multiple sim cards.
You can get a multiple of this 64 port bulk sms gsm modem with M35 module, 64 port gsm modem pool with IMEI change or go to AliBaba to request quotes for custom sms gsm modem. The Alibaba vendors list in 128 port multi sim bulk sms gsm modem may give you some ideas on how you can contact the seller to customize for your order.
I hope this helps.