3Com NBX 100 Administrator's Manual page 43

When you place a call to an external telephone number, the system can
use these pretranslator steps to create the full 10-digit number:
1 Remove (stripLead) the first two digits (20) from the internal extension
number of the telephone making the call.
2 Add (prepend) the digit sequence 50855542 to the two remaining digits,
creating the full DDI/DID telephone number.
3 Pass the full number to the telephone company.
Example: To transmit Calling Line ID Presentation (CLIP) information on
outgoing calls, you can define a pretranslator that transforms internal
extensions into full telephone numbers (the numbers that someone
external to the company uses to dial in). Assume that you are using
telephone extension numbers from 1000 to 1099 and that only the last
two digits match the DDI/DID (Direct Inward Dial/Direct Dial Inward)
numbers that are assigned to the company. You can define a
pretranslator to remove (stripLead) the first two digits from the internal
extension number and add (prepend) the appropriate digit string. This
pretranslator constructs the full telephone number.
Example: If you use two different long-distance carriers at different times
of the day to save costs, you can prepend different digit sequences to the
outgoing dialed number to select which carrier you want. If you prepend
1010321 between the time the business opens and 3:00 p.m., you select
one long-distance carrier. If you prepend 1010220 from 3:00 p.m. until
the next time the business opens (including weekends), you select the
other carrier and obtain a lower rate.
To tell the system which outgoing pretranslations you want to perform,
you define digit manipulation operations (append, prepend, replace,
stripLead, or stripTrail) in the Routes section of the dial plan configuration
file. You can define these commands for both destination routes and
timed routes. For more information on configuring pretranslators, see
"Managing Dial Plan Pretranslators"
Dial Plan Pretranslators
on page 64.
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