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New Member

ISDN calls don't work

Hello all,

I'm having problem with ISDN backup on 2 routers (same platform, same IOS but different errors). Everytime I try to place calls (via interesting traffic or "isdn test call interface") I get following message from debug:

Aug 24 11:21:50.482 MET: ISDN BR0/0/0 Q931: Ux_DLRelInd: DL_REL_IND received from L2

Aug 24 11:21:50.482 MET: ISDN BR0/0/0 **ERROR**: host_disconnect_ack: Call rejected cause Temporary failure(0x29) call id 0xA2F5


Aug 24 12:28:51.843 MET: BR0/1/0 DDR: Attempting to dial XXXXXXXXX

Aug 24 12:28:51.843 MET: ISDN BR0/1/0 EVENT: UserIdle: callid 0x810B received ISDN_CALL (0x0)

Aug 24 12:28:51.843 MET: ISDN BR0/1/0 EVENT: process_bri_call: call id 0x810B, called_number XXXXXXXXX Guid A48A9D1C810E speed 64, call type DATA, bchan -1 clng_num none

Aug 24 12:28:59.847 MET: ISDN BR0/1/0 EVENT: process_rxstate: ces/callid 1/0x810B calltype 1 HOST_DISCONNECT_ACK

Aug 24 12:28:59.847 MET: ISDN BR0/1/0 **ERROR**: host_disconnect_ack: Unfound B-channel on Disconnect_Ack call id 0x810B

Aug 24 12:28:59.847 MET: BRI0/1/0: wait for isdn carrier timeout, call id=0x810B

The whole output you can find in attachment together with output from "sh isdn status". Below is configuration of BRI and Dialer interface:

interface BRI0/0/0

bandwidth 64

no ip address

encapsulation ppp

dialer pool-member 10

no snmp trap link-status

isdn switch-type basic-net3

isdn point-to-point-setup

no keepalive

no fair-queue

no cdp enable

ppp authentication chap

ppp multilink


interface Dialer10

bandwidth 64

ip unnumbered Loopback0

ip accounting output-packets

encapsulation ppp

dialer pool 10

dialer remote-name XXXXX

dialer idle-timeout 60

dialer string XXXXXXXXX

dialer-group 1

no fair-queue

no cdp enable

ppp authentication chap

no ppp chap wait

ppp multilink


Both routers are 2811 running IOS 12.4(9)T1.

I have exactly the same BRI configuration on 2851 with different IOS version/different location and it works fine for me.

Do you have any ideas?



New Member

Re: ISDN calls don't work

1st router looks fine.

2nd router L1 status is DEACTIVATED

If the show isdn status command indicates that the L1 status is DEACTIVATED, then the router is not establishing an L1 connection to the Telco ISDN switch.

Perform these steps, and after each step, issue the show isdn status command to check if L1 is up (ACTIVE):

Issue the shutdown command, followed by the no shutdown command on the BRI interface in question.

This will ensure that the BRI interface is not administratively down. You can also issue the clear interface bri number command to reset the interface.

Verify that the backup interface command is not configured under the BRI interface. That command deactivates the BRI interface until the backup is initiated. If necessary, issue the no backup interface interface_type interface_number command to remove it.

Issue the show isdn status command to check if the switchtype for the interface is correctly configured. If the switchtype is either not configured or configured incorrectly, configure it on the interface.

If this is not helping it might be an issue with ISDN line try to call that ISDN no and make sure if calls are going through ir else please work with telco to Fix the issue

New Member

Re: ISDN calls don't work

1st router looks fine --> but just the output of "sh isdn status" I suppose.

I already cleared ISDN BRI interface a couple of times together with "shut" and "no shut" again. But I got still the same status, nothing changed.

I haven't configured "backup interface" command in my routers configuration.

And if the BRI interface is configured as "shutdown" - L1 looks as shutdown as well "Layer 1 Status: SHUTDOWN".

ISDN switchtype is configured properly, no doubt about it.

If L1 status shows "DEACTIVATED" it does not really means that the L1 doesn't work because I have on another router exactly the same L1 status "DEACTIVATED" and when I try to call the number which connected to this port routers connect each other without any problem. Then after connection time out the L1 status of this interface hold "ACTIVE" for a while and then turn back to "DEACTIVATED" again.

I thing there is another problem somewhere...IOS version or TELCO problem may be.

I went through a couple of ISDN document posted on CISCO website, but haven't found any satisfactory information.

Any other things to test?

But anyway I will try to contact someone from telco company.



New Member

Re: ISDN calls don't work

Here is a link from CISCO KB about BRI L1 "DEACTIVATED" status...