Fuse - Fuse is a UX tool suite for mobile app designers and developers.
Twilio - Brings voice and messaging to your web and mobile applications.
Dropsource - Mobile development platform for building native iOS & Android apps
MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.
GoodBarber - GoodBarber is a mobile app creation platform.
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates