Callmama - Get cheap international calling, international virtual number, Call Mama Gives an added advantage to send message and make calls to non-user of Callmama App.
Twilio - Brings voice and messaging to your web and mobile applications.
CallHippo - Easy to use Phone System with World-Class Support
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
Numero eSIM - Numero eSIM is a phone-number app that makes voice and data possible anywhere in the world, for free.
BulkSMS - SMS messaging service provider offering two-way SMS communication services.