User Extensions
To be able to make or receive calls on a 'phone' User Extensions are needed. A typical office setup will have a User Extension per staff member (and perhaps a common extension for reception).
Each User Extension features:
A three digit extension code which can be used for in-call transfer or calls between extensions.
A VoIP line to which a SIP compatible desk phone may be attached for making and receiving calls.
A Phone line which is used to answer calls on regular phones such as a mobile or landline (call transfer is supported but you can't originate calls).
Personal Voicemail which is delivered any email address.
Consider a small business with three staff; John, Jill and Frank.
Each staff member is given their own User Extension. John with only his mobile, Frank with a VoIP desk phone and Jill has a mobile phone and VoIP desk phone.
We shall use this typical scenario to show how User Extensions are used and managed.