3Com 3C10402B Administrator's Manual page 164

164 C 8: PSTN G
HAPTER
C
ATEWAY ONFIGURATION
Ordering DID, CLIP, and MSN Services
When you order a:
BRI line with DID (Direct Inward Dial) capability, Calling Line ID
■
Presentation (CLIP), or MSN services
E1 line with DID (Direct Inward Dial) capability, Calling Line ID
■
Presentation (CLIP), or MSN services
T1 line with DID (Direct Inward Dial) capability
■
the local telephone carrier assigns a block of telephone numbers to you.
Usually, you can request a specific range of numbers, but sometimes the
carrier assigns numbers other than the ones you request.
You might be able to request that the local telephone carrier pass you a
specific number of digits for each incoming telephone call. Sometimes
the carrier does not offer any choice. In either situation, you need to
know how many digits the carrier passes.
Example: Carriers commonly pass either the last three digits or last four
digits of the number for each incoming call.
Sometimes the last digits of the telephone numbers that the carrier
assigns to you do not match the telephone extension numbers you want
to use for internal calls. Create entries in your dial plan configuration file
to trans- late the incoming numbers into the corresponding extension
numbers.
Example: You want to use internal extensions from 4000 through 4999,
but the local telephone carrier assigns you numbers from 617-555-3500
through 617-555-4499. You can create translator entries in the dial plan
configuration file to translate an incoming digit sequence such as 3795
into extension number 4295, and a sequence such as 4213 into 4713.
The configuration requires several translator entries to manage subsets of
the total range. A unique set of entries would manage incoming digit
sequences from 3500 through 3599, from 3600 through 3699, and each
of the other sequences in which the first two digits were unique in the
range from 37XX through 44XX.
If the DDI/DID (Direct Inward Dial/Direct Dial Inward) numbers match your
internal extension numbers, the translator entries in your dial plan
configuration file can be much simpler.