| Paul Choi 2007-02-08, 7:11 pm |
| >From GWGK ->
Forward Digits
You can achieve more precise control over the number
of digits in the called number that are transmitted to
the PSTN with the following command, which applies
only to POTS dial peers:
forward-digits [number | all | extra]
where
number gives the number of digits to be forwarded.
all means to forward all digits.
extra tells the gateway to forward any digits that are
longer than the length of the destination pattern.
This command lets you specify the exact number of
digits to be forwarded. If the number of digits
presented exceeds the number allowed, the rightmost
digits are sent. One place this can be useful is when
you must dial a code (such as 9) to reach an outside
number, and there is an emergency situation. The
previous section showed how to ensure that the entire
emergency number (such as 911) is sent. In an
emergency, a person might be confused about whether to
dial the outside code. That is why dial peers are
typically set up to match both the emergency number,
and that number plus the code number. If the
destination pattern of a dial peer is 9911, you should
send only 911. You can use the forward-digits command
to transmit only the last three digits, 911, to the
PSTN.
The following examples show what digits are sent when
you dial the number 111-222-3333 and use various
options of the forward-digits command.
For this first case, the rightmost seven digits,
222-3333, are sent.
Miami(config)#dial-peer voice 111 pots
Miami(config-dial-peer)#destination-pattern 111222....
Miami(config-dial-peer)#forward-digits 7
With the configuration that follows, the entire
number, 111-222-3333, is sent. This is an alternative
to using the no digit-strip command shown in the
previous section.
Miami(config)#dial-peer voice 111 pots
Miami(config-dial-peer)#destination-pattern 111222....
Miami(config-dial-peer)#forward-digits all
Finally, with the final configuration that follows,
because the destination pattern is now six digits long
and the dialed number is ten digits, the "extra"
digits3333are sent.
Miami(config)#dial-peer voice 111 pots
Miami(config-dial-peer)#destination-pattern 111222
Miami(config-dial-peer)#forward-digits extra
Prefix Digits
In some cases, you might need to transmit more than
the dialed digits of a called number. For example,
perhaps a call that would normally go across your VoIP
network needs to be rerouted through the PSTN,
requiring the addition of the appropriate area code
and prefix. Or, a destination pattern might specify
the first six digits of the number, with wildcards for
the other digits. By default, those six digits are
stripped. You can use the prefix string command to
replace some of those digits. This command is given
under dial-peer configuration mode, and it is only for
POTS dial peers. The prefixed string can be any number
from 0 to 9 and a comma that inserts a one-second
pause. The gateway prefixes digits after the outgoing
dial peer is matched and after any digits are
stripped, but before it sends out the call.
In Example 10-1, long-distance calls need to go to a
particular carrier and must have a separate dial peer
from external local calls. The destination pattern is
91 to capture long-distance traffic; however, the PSTN
needs the number 1 transmitted as part of the called
number to route the call properly. Thus, the prefix
command is added to replace that digit.
Example 10-1. Prefixing Digits to an Outgoing Call
Miami(config)#dial-peer voice 91 pots
Miami(config-dial-peer)#destination-pattern 91T
Miami(config-dial-peer)#prefix 1
Miami(config-dial-peer)#port 1/0:23
When a user dials the outside long-distance number
9-1-111-222-3333, the digits are manipulated before
being sent to the PSTN. The original digits 9 and 1
are stripped, and a 1 is prefixed to the remaining
number. Thus, the PSTN receives the number
1-111-222-3333.
So in short, it looks like either method would work
but I believe it is much more common to use
'forward-digits' in your situation....just like with
9911, *I* would personally use 'forward-digits 3'.
Paul
--- Lelio Fulgenzi <lelio@uoguelph.ca> wrote:
> Just wondering if anyone has any advice or comments
> regarding using forward-digits vs prefix in
> dialpeers. Anyone find that one is easier to
> maintain or troubleshoot?
>
> For example, if I want to send out 411 calls, I have
> these two options as far as I can tell:
>
> !
> dial-peer voice 411 pots
> destination-pattern 9411
> port 3/0:23
> forward-digits 3
> !
>
> OR
>
> !
> dial-peer voice 411 pots
> destination-pattern 9411
> port 3/0:23
> prefix 411
> !
>
> Comments?
>
>
--------------------------------------------------------------------------------
> Lelio Fulgenzi, B.A.
> Senior Analyst (CCS) * university of Guelph *
> Guelph, Ontario N1G 2W1
> (519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
>
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>
> ...there's no such thing as a bad timbit...
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> cisco-voip@puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-voip
>
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