Kuwait mobile network operators (MNOs) have strict rules. You must use pre-registered SenderID. Traffic must be bought from local service provider/reseller.
SMS messages from International companies like: twilio, bulksms, infobip, clickatell, and many others, does not reach Kuwait and gets filtered or blocked.
It is best to work with local SMS provider/reseller from Kuwait like kwtSMS to guarantee delivery. kwtSMS also has global coverage.
See detailed comparision between Twilio with kwtSMS
+ Do you have WhatsApp services?
+ Do you provide numbers/database for marketing?
+ Can I send international/GCC SMS, and what are the rules?