Information Technology Reference
In-Depth Information
Example 6-12
Configuring a North American PSTN Dial-Plan
VOICE_RTR(config)#
dial-peer voice 90 pots
VOICE_RTR(config-dial-peer)#
description Service Dialing
VOICE_RTR(config-dial-peer)# destination-pattern 9[469]11
VOICE_RTR(config-dial-peer)#
forward-digits 3
VOICE_RTR(config-dial-peer)#
port 1/0:1
VOICE_RTR(config-dial-peer)#
exit
VOICE_RTR(config)#
dial-peer voice 91 pots
VOICE_RTR(config-dial-peer)#
description 10-Digit Dialing
VOICE_RTR(config-dial-peer)#
destination-pattern 9[2-9]..[2-9]......
VOICE_RTR(config-dial-peer)#
port 1/0:1
VOICE_RTR(config-dial-peer)#
exit
VOICE_RTR(config)#
dial-peer voice 92 pots
VOICE_RTR(config-dial-peer)#
description 11-Digit Dialing
VOICE_RTR(config-dial-peer)#
destination-pattern 91[2-9]..[2-9]......
VOICE_RTR(config-dial-peer)#
forward-digits 11
VOICE_RTR(config-dial-peer)#
port 1/0:1
VOICE_RTR(config-dial-peer)#
exit
VOICE_RTR(config)#
dial-peer voice 93 pots
VOICE_RTR(config-dial-peer)#
description International Dialing
VOICE_RTR(config-dial-peer)#
destination-pattern 9011T
VOICE_RTR(config-dial-peer)#
prefix 011
VOICE_RTR(config-dial-peer)#
port 1/0:1
VOICE_RTR(config-dial-peer)#
exit
Two commands in this syntax deal with the automatic digit-stripping feature of POTS dial
peers:
forward-digits
<
number
> and
prefix
<
number
>. The
forward-digits
<
number
>
command allows you to specify the number of right-justified digits you want to forward.
Notice the first dial peer 90 in Example 6-12. With a destination pattern of 9[469]11, the
router would automatically strip the 9 and the two 1s from the pattern before sending the
call. By entering the command
forward-digits 3
, the router forwards the right-justified
three digits (411, 611, or 911) and only strips the 9.
The
prefix
<
number
> command adds any specified digits to the front of the dialed num-
ber before routing the call. This is useful for dial peer 93 in Example 6-12. Because inter-
national numbers can be a variable length, it is impossible to tell what value to enter for
the
forward-digits
command. By using the
prefix 011
command, the automatic digit-
stripping feature of POTS, dial peers strip the explicitly defined 9011 digits from the pat-
tern, and the
prefix
command then adds the 011 back in its place.
Private Line Automatic Ringdown
Although not directly related to dial peer configuration, Private Line Automatic Ringdown
(PLAR) configurations rely heavily on existing dial peers to complete a call. Ports configured
with PLAR capabilities automatically dial a number as soon as the port detects an off-hook
signal. The most obvious use for PLAR configurations is emergency phones in locations such
as company elevators or parking garages. Example 6-13 designates x1101 (shown in Figure
6-8) as a PLAR extension that immediately dials x1102 as soon as a user lifts the receiver.
