User Extensions
The settings are mostly the same for SIP phones, Analog phones, and Virtual extensions. Each extension has a corresponding Extension Suite account (/main):
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Virtual Extension. An extension without a phone or a Switchboard. This type of extension behaves like a SIP Phone extension except it does not have a Switchboard and it does not show the phone as Unreachable in System Status. This is useful as a general voicemail box.
See also these articles: