Plivo – Open Source Communication Framework for Creating Voice Based Apps
Plivo is a free and open-source communication framework for creating voice-based applications that give you telecommunication features such as make and receive calls from any phone, Skype, and Gtalk or send SMS to applications.
The developer can build voice-based applications such as IVRs, Billing System, Voicemail, Click to Call, etc. It directly interacts with the phone system using your existing web development skills and infrastructure to program custom business logic (via HTTP) to control incoming and outgoing phone call instances.
Plivo is a 100% FOSS framework built on the open-source telephony platform FreeSWITCH and is written in Python, event, and Flask. plivo framework is the perfect open-source alternative for Twilio.
Also, FreeSWITCH provides native support for Skype, SIP, H.323, Google Talk, and Google Voice means that applications developed by Plivo can easily compatible with these platforms.
Download: Plivo communication framework