From Works Out Software:
You don't have to spend thousands on a telephone system. CallButler Professional For Skype is a complete Skype based small business telephone system that can be setup in just 10 minutes. It has support for PBX, voicemail, auto-attendant, IVR, music on hold, custom scripting, and integration. With CallButler you can implement telephony features that businesses 10X your size use.