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Twilio is a web-service API that lets you use your existing web languages and skills to build voice and SMS applications. We focus on building a simple, powerful, pay-as-you-go communications platform so that you can focus on what you do best.

Nexmo provides innovative communication APIs that bridge traditional voice and text services with cloud communications.

Plivo is a voice and SMS API platform that enables developers and enterprises to build powerful apps with great features. With 24/7 free tech support and low prices, Plivo can help your business scale globally.

Unchained resources : Voximal integrates cloud speech services like Google Speech API, IBM Watson SpeechToText, Azure Bing Speech, but keeps on-premise capability thanks to UNIMRCP connector.

CALLR is a voice and messaging API available through REST, JSON-RPC and SDKs (PHP, Python, Ruby, Go, Node.JS, Swift, Java, .NET). It's built with many features made to help brands create smarter interaction with their customers and prospects. CALLR's services are available worldwide in 220+ countries. Two web interfaces, SENDR (Campaign Management) and CALLTRACKR (calltracking and click-to-call) are available to offer access to CALLR's services without having to code.Here are our six main business use cases:SIP Trunking (Outbound and inbound calls at scale) - Conveniently handle my important outgoing call needs. Face any international needs with an adaptive solution that matches my location, and network situation.User Acquisition and Engagement (Outbound calls and SMS campaigns) - Generate online and in-store traffic and keep users engaged using automated and scalable communications methods. Easily broadcast news about sales and events to my customer base.Notifications (Personalized outbound calls and SMS) - Send personalized messages to your customers at key steps of their journey. Notify them of main events and make sure they receive your messages.Custom IVR (Inbound or outbound calls control menu) - Create a smart mapping to route incoming calls according to the rules I set. Make sure each call I receive is handled the quickest and most efficient way.Call Tracking (Inbound calls source identification) - Track incoming calls activity and know where my users found my number. Track calls generated for and routed to a third party.Person to Person Communication (Users calls and SMS safeguarding) - Easily allow my users to exchange with each other on their usual channels. Frame the interaction to ensure its security and keep it smooth. »

Sinch is a powerful voice and messaging SDK that lets you bring your apps to life with VoIP and WebRTC technology. Simplicity is at its core and you can get your first app up and running in a few lines of code and a matter of minutes.

TollFree and IVR are the cloud telephony services which help you to improve your performance and you can provide customer service from anywhere. Get started now!