XiVO!

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.

Wazo is mainly an IPBX that provides communication services such audio, video, and instant messaging based on the use of standard network technologies such as the TCP/IP protocol. It is interoperable with most market telephony systems and gives users access to flexible and advanced services without requiring specialized hardware.

3CXPhone is a free VoIP phone available for Windows, iPhone or any Android based smart phone such as Google Nexus, Sony Xperia, Motorola Droid or Samsung Galaxy. Connect 3CXPhone to a VoIP provider or to a VoIP PBX (for example 3CX Phone System) to make calls to any VoIP, mobile or landline number.

FreeSWITCH is a scalable open source cross-platform telephony platform designed to route and interconnect popular communication protocols using audio, video, text or any other form of media. It was created in 2006 to fill the void left by proprietary commercial solutions. FreeSWITCH also provides a stable telephony platform on which many telephony applications can be developed using a wide range of free tools.

Incredible PBX is a secure and feature-rich implementation of the Asterisk® PBX. By rethinking the PBX security model from the ground up.

Yate is a softswitch (concept of separating the network hardware from network software).

Starfish PBX aims to be an open source alternative to Digium’s Switchvox. The goal is to have a software equivalent to which we can add additional functionality like:

Elastix is an open source Unified Communications Server software that brings together IP PBX, email, IM, faxing and collaboration functionality. It has a web interface and includes capabilities such as a Call Center software with predictive dialing.

VoipSwitch is a SoftSwitch System with routing and billing, with SIP protocol support (in older versions also H323).

PBX in a Flash is a PBX system based on Asterisk, FreePBX and CentOS, coming as an ISO download. A two stage installation process allows for more flexibility for the installation of the PBX specific components. The Asterisk components are compiled from source during the install process which allows for easier adaptions later on. The system is update-able without re-install. A script collection on pbxinaflash.org allows for easy extension of the base system.

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.

A SIP based implementation of a PBX / unified communications system.

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. »

FreeSentral is a full IP PBX consisting of a Linux Distribution, an IP PBX and a Web Graphical User Interface for easy configuration