(2) When capitalized as , an open sourcePBXdaemon that runs on Linux. Asterisk is a complete PBX contained within software and can interoperate with almost all standards-based telephony equipment using comparatively inexpensive hardware. Asterisk supports a wide range of TDMprotocols for the handling and transmission of voice over traditional telephony interfaces and also supports US and European standard signalling types used in standard business phone systems.