textPlus
Description: textPlus is a free texting and calling app for Android and iOS. It allows users to send SMS texts and make phone calls for free over WiFi. Some key features include free unlimited texts and calls to any phone number in the US and Canada, voicemail transcriptions, group messaging, and integrating your existing phone number.
Type: software
Pricing: Free
Yate - Yet Another Telephony Engine
Description: Yate is an open-source telephony engine and server for VoIP and legacy telephone infrastructure. It supports multiple protocols and interfaces for building communications solutions.
Type: software
Pricing: Open Source