Mitel 1000 Owner's Manual page 28

Programming Class of Service Codes
The definition of what constitutes Restricted, Allowed, National &
International calls, is determined by the leading digits of the dialed
number.
Thus, for example, numbers beginning with '011xx' are International
calls. Numbers beginning one '1xx' are National calls.
The definition of Allowed and Restricted codes is at the user's
discretion.
50 entries can be configured in the dialing codes for International,
National, Allowed & Restricted numbers.
These dialing rules can be configured manually. See 'To change the
Allowed, Restricted, National and International codes, click here' on
the 'Edit Class of Service Extensions' page.
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