Deutsche Telekom BRI - H323 - CCM - Overlap Receiving

Unanswered Question
Jul 14th, 2008

Hi Guys,

I know that German telco's commonly use Overlap send and receiving.

I have a 2811 as a voice gateway using H323 to talk to our CCM cluster.

The office uses a 10 digit number for the main reception switchboard and an extra digit for the DDI range for the extensions...


69 12 345 100 - reception

69 12 345 1001 - 1099 - DDI range

I'm seeing two things from the ISDN debugs...

Calls from within Deutsche Telekom seem to send the called party number for the DDI in the first setup message complete.

Calls from another Telco, come in with the first 10 digits, and then send the 11th digit in a separate setup message.

It tries to match the 2nd digit only at this point, and returns unallocated unassigned number.

What is the best practice config for Deutsche Telekom and this scenario?

interface BRI0/0/0

no ip address

isdn switch-type basic-net3

isdn overlap-receiving T302 500

isdn point-to-point-setup

isdn incoming-voice voice

isdn send-alerting

isdn sending-complete

isdn outgoing-voice info-transfer-capability 3.1kHz-audio

isdn static-tei 0

trunk-group pstn

dial-peer voice 1 pots

trunkgroup pstn

description *** inbound pstn dial-peer ***

translation-profile incoming from_pstn

incoming called-number .


I'm wondering if my incoming called-number is the problem. But this is the standard practice to avoid hitting the default dial-peer...

I will continue to debug.. but does anyone have experience with Deutsche Telekom specifically, and how they provide their circuits, and the best practice for setting up the CPE?


I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Tim Smith Mon, 07/14/2008 - 06:24


dial-peer voice 501 voip

description to *** to ccm ***

preference 1

destination-pattern 10..

voice-class codec 88

voice-class h323 77

session target ipv4:x.x.x.x

There is a translation on the inbound dial peer...

It takes the digits received from PSTN and turns them into a 4 digit extension number..

Using test voice translation always gives the correct result here as well.



Paolo Bevilacqua Mon, 07/14/2008 - 08:37


the problem is that trawlation-rule have problem working with overlap-receiving.

What is likely happening, is that when root number is received, it is translated, but subsequent digits are not.

The workaround is to :

1. do not not have main number to overlap with DIDs.

This way the translation cab be made to simply to nullify the common part, eg:

rule 1 /^5551234/ //

Tim Smith Tue, 07/15/2008 - 02:54


Does overlap receiving with MGCP and translation patterns in CCM work better?

With H323 on the inbound dial peer...

What about using a T in the incoming called number pattern? Will that collect all the digits and then

Currently they have used some numbers that overlap between the main.. I might be able to change this hopefully.. as I think it is a bit strange anyway.

I have seen some Deutsche Telekom guys knocking about on Netpro... How would they suggest CPE to be configured for this optimally...



Paolo Bevilacqua Tue, 07/15/2008 - 03:11


No idea about MGCP. I can suppose that it would be able to handle the overlapping issues better that H.323 and the translation-rules.

I've had the same issue (with CME) until I renounced the idea to use 555-4000 for the main number and 555-4000-xx for the DIDs.

Customer was happy with that and all is good.


This Discussion