ISDN BRI Anlagenanschluss trunk help / hilfe

I’m trying to help a customer set up a system (Elastix 2.0 with Asterisk 1.6.2) in Germany connected to two ISDN BRI lines but I am unable to get the ISDN trunks working. :frowning:

I have been told that the ISDN lines are ‘Anlagenanschluss’ lines and that the ports on the ISDN card (OpenVox B200P) have been connected to an NTBA via straight through Ethernet cables. The lines are provided by Deutsche Telekom.

I have tried a number of different configuration parameters and have tried both mISDN and dahdi wcb4xxp drivers but I can’t get the ISDN trunks working. The issues is that I live in the UK and am not sure what the configuration settings for ISDN lines in Germany should be. At the moment I don’t know if the issue is with the configuration, the driver software, or the ISDN lines themselves!

The most success I have had is with the dahdi wcb4xxp driver configured in TE PTP mode (bri_cpe). In this mode the lines come up and show up/active. However, as soon as an outbound call is placed the lines go down. The error messages received are “MDL-ERROR (F), SABME in state 7” and “chan_dahdi.c: pri_find_dchan: No D-Channels available! Using…” I have tried adding the ‘pmp_l1_check=no’ parameter but the problem remains.

I have looked at the intense debug output and the server is receiving UI frames on SAPI=63, TEI=127, which I understand are for PTMP setup not PTP setup. However, I have also tried PTMP signalling (bri_cpe_ptmp) but in this configuration the lines stay down and do not come up at all. The debug output just shows “Received MDL message” every second or so but the lines do not come up and can’t be used for calls.

I can post the full configurations and debug/log outputs, but what I would really like is:

  1. Confirmation that connecting the ISDN ports on the Asterisk server to the NTBA in TE mode using a straight-through cable should work OK (as I have seen some posts on the Internet that talk about using ISDN crossover cables in NT mode instead).

  2. An example working configuration (mISDN or dahdi) for German ‘Anlagenanschluss’ Deutsche Telekom ISDN lines so I know what the setting should be for things like the correct mode (i.e. ptp, ptmp) and pridialplan (i.e. national, local, unknown).

If anyone can help provide the information mentioned above then I would be extremely grateful!

Thanks / Danke,

[I have also submitted this post on the Elastix forum]

This issue has been resolved; it turned out to be a cabling/connectivity issue. There are two ISDN lines but Deutsche Telekom only provided one NTBA (NT1) box. The IT contractor on site was told by the Deutsche Telekom engineer to connect both ports on the one NTBA supplied into the Asterisk box (which we only just found out today).

This was obviously never going to work in TE PTP mode as the Asterisk PBX was operating as if it was connected to two different lines, but was in fact connected to the same line via two different ports. This caused the lines to go up/down when calls were received/made as Asterisk tried to activate the same 2 B channels over two different ports so was never able to establish a call.

I had assumed that the ports on the ISDN card were connected to two different NTBA boxes (not the same one!), and as the ports were up/active initially I didn’t think it could be a cabling issue. It just goes to show – Never assume anything!!!

I can confirm now that Anlagenanschluss ISDN BRI lines work perfectly with Elastix 2.0 64bit (Asterisk using both dahdi ( and the mISDN driver ( in TE PTP mode, with each port connected to a different NTBA using a standard straight through Ethernet cable.

Working mISDN config:


<mISDNconf> <module poll="128" debug="0" timer="no">hfcmulti</module> <module debug="0" options="0">mISDN_dsp</module> <devnode user="root" group="root" mode="644">mISDN</devnode> <card type="BN4S0" dtmf="yes"> <port mode="te" link="ptp">1</port> <port mode="te" link="ptp">2</port> <port mode="te" link="ptp">3</port> <port mode="te" link="ptp">4</port> </card> </mISDNconf>




senddtmf=yes ; Produce DTMF Tones ourselves
msns=* ; listen for any multiple subscriber number (MSN)


ports=1,2 ; define ports
context=from-pstn ; context for incoming calls[/code]

Working dahdi config:


[code]# Span 1: B4/0/1 “B4XXP (PCI) Card 0 Span 1” (MASTER)

termtype: te


Span 2: B4/0/2 “B4XXP (PCI) Card 0 Span 2”


termtype: te


Global data

loadzone = de
defaultzone = de[/code]

overlapdial=yes pridialplan = local nationalprefix = 0 internationalprefix = 00

[code]; Span 1: B4/0/1 “B4XXP (PCI) Card 0 Span 1” (MASTER)
switchtype = euroisdn
signalling = bri_cpe
channel => 1-2

; Span 2: B4/0/2 "B4XXP (PCI) Card 0 Span 2"
switchtype = euroisdn
signalling = bri_cpe
channel => 4-5[/code]