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New Member

VG200 and overlap-receiving


We have a VG200 connected to a PABX via ISDN BRI interfaces.

When the PABX sends dialed numbers in the overlap mode, the VG200 only analyzes the first digit of the called number and disconnects the call with cause = "unallocated/unassigned number".

The BRI interface has been configured with "Isdn overlap-receiving T302 2000".

- Dial-peer that matches the called number is :

dial-peer voice 89 voip

destination-pattern 89T

voice-class codec 1

session target ras

no vad

- Dial-peer that matches the calling number is :

dial-peer voice 123456 pots

destination-pattern 123456....

port 1/0/1

The VG200 is running IOS version 12.2(2)T.

In advance thanks for any help.


New Member

Re: VG200 and overlap-receiving

Configuring Overlap receiving on the D-channel changes the way routers behave when receiving ISDN calls. The router will respond to the setup message with a SETUP ACK. This informs the network that it is ready to receive further information messages containing additional call routing elements. "Unallocated/unassigned number" problem occurs when the destination number used in the dial peer is not of the same length as the called number being received. This type of dial plan will work without problems in En bloc mode, but with Overlap receiving the router, it will try to place the call after enough digits have been received to match the destination number. In this case, after the 5 has been received. To prevent this from occurring the "T" terminator should be placed after the digits in the destination pattern. This causes the router to wait for the T302 timer to expire after each digit's reception, allowing the full number to be collected before placing the call.

You can go through the following link to get more assistance:

New Member

Re: VG200 and overlap-receiving


Thank you for the reply.

I think I have taken into account the 2 things :

1) configure the dial-peer that matches the called number with the "T" terminator :

dial-peer voice 89 voip

destination-pattern 89T ! <= T terminator


2) readjusted the T302 timer as shown int the document about "Overlap Receiving - Unallocated/Unassigned number Error" :

BRI is configured with :

"Isdn overlap-receiving T302 2000"



Re: VG200 and overlap-receiving

you probably need the command 'direct-inward-dial' on the POTS dial peer 123456. This will tell the router to use the called number in the setup message or subsequent IE's and make the match on other dial peers.

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