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Designing Voice-over-Data Networks 603
Class of Service groups:
·
CoS1Lobby phone: No outside access; 1­800 only
·
CoS2Admin phone: Local only and 1-800 service
·
CoS3Sales phone: Local, long-distance
·
CoS4Manager's phone: No restrictions
Handling incomplete calls, voice mail, redirected calls, and 911 calls are also the responsibility
of an efficient dial plan.
Figure 16-6 shows adding and stripping digits for a dial routing plan.
Figure 16-6
Dial Routing Plan
Examine the figure in regards to outgoing calls in the first example:
·
Strips digits or adds access codes to call the PSTN.
·
Caller keys in 9-1-212-460-1234.
·
PBX strips the 9 and adds 10-10-288 to rout the signal to dial around the long-distance
service.
Look again at Figure 16-6 for the second example:
·
Strips and adds digits on a network call.
·
Caller keys 9-1-714-313-1234 (1234 is the extension at the branch office serviced by the
tie-line).
·
PBX strips 91714313 and adds 843 (843 is the trunk access code to route the signal
through the tie-line).
9+1+212+460+1234
9+1+714-313-5678
(5678 is extension
at branch office
serviced by tie line)
Cafeteria phone
ÒCaller ID = Off-NetÓ
Caller ID=4567
9 stripped
10-10-288 Prepended
(a toll service
ÒDial Around ServiceÓ)
PBX stripped 91714313
and added 843
(Trunk access code-
call routed via tie line)
PBX strips caller ID
replaces with string
PBX strips
202-123
Received
Received
at branch
extension
Call to cafeteria phone
(DID) from 123-555-1212
Call from branch office
202-123-4567 via tie line
87200333.book Page 603 Wednesday, August 22, 2001 1:41 PM