An extension in asterisk is a user that is able to connect and use the system to place or receive calls, use voicemail and other features of asterisk. In order to define asterisk extension we should edit users.conf (Asterisk 1.4), iax.conf and sip.conf files.

There are just few conventions:

1) the extension must be numeric es. [123]
2) the callerid must be in the format "name <extension>"

example in you SIP or IAX.conf:

[123]
host=dynamic
qualify=yes
notransfer=no
secret=xxxxxxxxxx
type=friend
auth=md5
context=your extensions context
dtmfmode=rfc2833
requirecalltoken=no ;if iax
username=123
callerid=pippo <123>
mailbox=123@your voicemail context
disallow=all
allow=gsm
deny=0.0.0.0/0.0.0.0
permit=192.168.1.0/255.255.255.0
The extensions in Voix Manager are represented by buttons.
Extension Button Description

The Extension Button have 11 States.
The off hook state is only available for zap channels.
Pointing the mouse over the CallerIdName or the Voice mail icon will be displayed the relative ToolTip
Extension ToolTip
Right clicking the button will show the context menu with all the commands available
Extension ToolTip
Clicking the CallerIdName will be displayed the user detail window
Extension Available
Extension Available
Extension Unavailable
Extension Calling
Extension Ringing
Extension Active
Extension On Hold
Extension Parked
Extension On Queue
Extension Do not distrurb
Extension Do not distrurb
Extension Off Hook
Extension Available

Extensions and groups can be ordered via drag and drop, the extensions can also be moved from one group to another via drag and drop.