Open source PBX software that runs under Linux and other ... Supporting traditional telephony (TDM) as well as voice over IP (VoIP), Asterisk is written in C and uses the Unix standard POSIX ...

RingCentral MVP is a cloud business phone system that ... If you were to develop a PBX system using the Asterisk framework and have never used it before, you can access plenty of documentation ...

A VoIP-based PBX system that is hosted by a service provider over the Internet. All phone features such as auto attendant, voicemail and conference calling are handled in the cloud PBX datacenter.