There are 2 repositories under voip-from-php topic.
Google Voice call and sms access app, standalone or addon.
C++ linphone library implementation, callable from PHP
Auto Complete - Country Codes and Network Descriptions
TelecomsXChange Market View Rate API, VoIP Rates API, VoIP Providers and Carriers rates API
Make Outbound voice Calls via PHP on specified carriers or termination end points.
AGI tool for asterisk to display the caller-id-info for pickup on phones not ringing. Replaces the chronically broken "notifycid" feature of chan_sip
Get Seller or Buyer account live calls via API
Python example of the TelecomsXChange Voice Communication Api