User guide
 System Administrator’s Guide – Release 7.5 
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Toll Free 1-866-ALLWORX • 585-421-3850 • www.allworx.com 
Revised: April 9, 2013 
Page 40 
the extension automatically changes to x1104. A system extension of x231 adjusts to 
x1231.  
 Switching back from 4-digit extensions to 3-digit extensions is not recommended. If 
the switch is made, all extensions will be shortened to three digits by removing the first 
digit (e.g. an extension of x1205 will become x205). However, this can lead to conflicts 
(e.g. x1100 and x2100 would shorten to the same 3-digit extension). For this reason, 
switching from 4-digit extensions to 3-digit extensions will be prevented if there are any 
extensions outside the range of x1100-x1299. For sites using a non-default internal 
dial plan, all extensions must be in the range of x100 – x299. For example, if the site’s 
extensions are 4xxx – 5xxx, all extensions must be in the range of 4100-4299, in order 
to switch to 3-digit extensions. If there are extensions outside of this range but a switch 
from 4-digit extensions to 3-digit extensions is desired, all extensions that are outside 
the range must be changed or deleted. 
The following affects phone functions when the extension length setting is changed. 
The format of the number to dial is the same but the number of digits changes, 
depending on whether extensions are set to three digits or four digits. 
Function  Format†  3-digit 
Example† 
4-digit 
Example
1
Leave a voicemail  3 + extension  3199  31199 
Check voicemail  6 + extension  6199  61199 
Call forwarding  45 + extension  45199  451199 
Answer alternate 
extension 
7 + extension  7199  71199 
In addition to the changes in user and system extensions, the following server 
configurations automatically update when changing the extensions from three digits to 
four digits:  
•  Extension call routes including Internal Caller-ID checking 
•  Incoming outside line call routes 
•  DID mappings 
•  System Speed Dials (the Speed Dial extension doesn’t change but the extension 
that is dialed as a result changes) 
•  Speed Dial PFK (differs from Personal Speed Dial PFK) 
1
 Extensions may vary per system. If you are using a non-default Internal Dial Plan, consult the 
Phone Features tab of the My Allworx Manager page to determine what extensions are being 
used for the corresponding feature. 










