Twilio offers developers a powerful API for phone services to make and receive phone calls, and send and receive text messages. Their product allows programmers to more easily integrate various communication methods into their software and programs.
Nexmo connects your apps directly to carriers around the world. Integrate SMS and Voice messages using one simple API. Use Nexmo Verity to register users, verify transactions, and implement two factor authentication.
It gives powers to chat commerce by helping you reach and engage customers through SMS, WhatsApp and other social channels.
Plivo provides basic building block APIs in the form of Plivo XML and HTTP API, to create telephony apps, so developers can completely do away with learning the nitty-gritty of the telephony plumbing.