Extensions are at the core of every PBX. Extensions on the Vodia PBX have multiple numbers, DIDs and ANIs for inbound and outbound call identification. Each extension has a name, a company position and passwords for web and SIP access. Each extension may have its own timezone, web and IVR language and have an image associated with the extension which can be shown on VoIP phones that support showing a photo caller-ID. Extensions can have their own ringtone, permissions for various actions, address book and music on hold source.