For the Version 20 guide click here.
Log in to the 3CX Management Console
Select the "Users" tab from the 3CX Dashboard.
Select the "+ Add" button.
Fill in the following Extension information:
Extension: Extension Number
First Name: User's First Name
Last Name: User's Last Name
Email Address: User's Email (optional)
Mobile Number: User's Cell (optional)
Outbound Caller ID: Caller ID for outbound calls
If no caller ID is set then it will default to the trunk's caller ID.
There are many other settings that can be updated via the extension creator and editor: Voicemail, Forwarding Rules, Phone Provisioning, Phone BLFs, Options, and Extension Rights.