why does PRI need "forward-digits" command

Unanswered Question
Jul 6th, 2008

Looking at an example of routing calls to PRI first then FXO I found the following:


dial-peer voice 1000 pots

destination pattern 91..........

port 0/0:23

forward-digits 11

!

dial-peer voice 1001 pots

preference 1

destination-patterm 91..........

port 2/0/0

!


I thought the digits that matched the destination pattern were stripped when forwarded to the PSTN. In this example it seems that the "1" would not be sent to the PSTN and the call would fail. Also why does the PRI need the "forward-digits" command the the FXO doesn't?


Thanks,

Diego



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Paolo Bevilacqua Sun, 07/06/2008 - 09:48

All type of ports ports behave the same way. In the example above, calls via DP 1001 would fail because it has not "forward-digits", that is the commands that defines how many digits are sent to PSTN, no matter what is matched and what is not.


Another less known way to do that is the following:


destination-pattern 9[1][2-9][0-8].[2-9]......


And requires no "forward-digits" command. By the way the above is the correct DP for LD NANP.


DIEGO ALONSO Sun, 07/06/2008 - 10:27

I don't understand why your destination-pattern command doesn't require forward-digits but the others do. Can you provide more detail?


Thanks,

Diego


Paolo Bevilacqua Sun, 07/06/2008 - 10:39

If "forward-digits" (or "no digit-strip", that is equivalent to "forward-digits all") is applied, then the specified number of rightmost digits are sent, and no stripping per below actually occurs.


Else, stripping occurs:

Digits explicitly matched are stripped. Like 9 in my example.

Digits matched to patterns in square brackets, or to "." are not stripped.


In any case, if "prefix" is configured, it is sent before the digits.


It is a bit complicated but very powerful way to control number format and what is sent.




DIEGO ALONSO Sun, 07/06/2008 - 10:52

Yes, you are right about the complicated part. I guess I'll need to practice and experiment.


Thanks,

Diego


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