Craftwork - A collection of User Interface resources made by Craftwork
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
Chat by Stream - Build and ship in app messaging in a few hours
MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.
Rodman Mobile UI Kit - Premium colorful iOS templates designed for Sketch App
Plivo - Plivo simplifies your customer engagement.