Bandwidth - Bandwidth offers SIP trunking, Emergency communications, and Voice & Messaging APIs.
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
Voxbone - Fully compliant, enterprise-ready voice and SMS on demand. Build local presence on a global scale with elastic SIP trunks and phone numbers. Try for free.
MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.
Plivo - Plivo simplifies your customer engagement.
Telnyx - Telnyx is a cloud-based platform that offers access to carrier grade voice services over the internet.