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ISDN BR0 **ERROR** Temporary failure(0x29)


I've got a router at a customer's site that uses ISDN as a backup line. For some reason, I was able to successfully make a call this morning, but then trying again right after that call, I get the following error message when I try to make an isdn test call interface bri 0:

*Mar  5 01:47:58.143: ISDN BR0 **ERROR**: host_disconnect_ack: Call rejected cause Temporary failure(0x29) call id 0x8007

The ISDN line is a standard Point to Multipoint ISDN line from the Deutsche Telekom here in Germany. I've already had a technician on-site to look at the line, calls in and out work perfectly fine, but the Cisco router can't make a test call properly. I've already replaced the router because the thing wouldn't initiate a call when the main SDSL line went down.

Can anyone give me a hint?

Here's debug isdn events and debug isdn q931:

router#isdn test call int bri 0 [testnumber]


*Mar  5 02:00:38.379: ISDN BR0 EVENT: UserIdle: callid 0x800A received ISDN_CALL (0x0)

*Mar  5 02:00:38.379: ISDN BR0 EVENT: process_bri_call: call id 0x800A, called_number [testnumber], Guid C928DE00800D speed 64, call type DATA, bchan -1 clng_num none

*Mar  5 02:00:38.383: ISDN BR0 Q931: Applying typeplan for sw-type 0x1 is 0x0 0x0, Called num [testnumber]


*Mar  5 02:00:44.385: ISDN BR0 Q931: Ux_DLRelInd: DL_REL_IND received from L2

*Mar  5 02:00:44.389: ISDN BR0 EVENT: process_rxstate: ces/callid 1/0x800A calltype 1 HOST_DISCONNECT_ACK

*Mar  5 02:00:44.389: ISDN BR0 **ERROR**: host_disconnect_ack: Call rejected cause Temporary failure(0x29) call id 0x800A


and here's the relevant config data:

router#show run int bri0

Building configuration...

Current configuration : 251 bytes


interface BRI0

description Dial Backup Interface

bandwidth 128

no ip address

encapsulation ppp

dialer pool-member 2

isdn switch-type basic-net3

isdn twait-disable

isdn point-to-point-setup

ppp authentication chap callin

ppp multilink


gs01-kempten#show run int dia2

Building configuration...

Current configuration : 420 bytes


interface Dialer2

bandwidth 128

ip unnumbered Loopback0

ip access-group 120 out

encapsulation ppp

load-interval 30

dialer pool 2

dialer string 0[testnumber]

dialer string [testnumber]

dialer watch-group 1

dialer-group 2

ppp authentication chap callin

ppp chap refuse

ppp pap sent-username user@realm password pass

ppp ipcp dns request accept

ppp multilink

no cdp enable


dialer watch-list 1 ip [watched IP]

dialer watch-list 1 delay route-check initial 600

dialer watch-list 1 delay connect 180

dialer watch-list 1 delay disconnect 120

access-list 120 remark "deny voice via Backup"

access-list 120 deny   ip any [voice net]

access-list 120 permit ip any any

We have this exact configuration running perfectly in dozens of other locations, so I really don't know what the deal is here.


Here's the software version:

Cisco IOS Software, C870 Software (C870-ADVENTERPRISEK9-M), Version 15.1(3)T, RELEASE SOFTWARE (fc1)

Technical Support:

Copyright (c) 1986-2010 by Cisco Systems, Inc.

Compiled Tue 16-Nov-10 04:45 by prod_rel_team


I turned on debug isdn q921 and found this:

*Mar  5 02:55:30.710: ISDN BR0 Q921: User TX -> IDREQ ri=45637 ai=127

*Mar  5 02:55:32.710: ISDN BR0 Q921: User TX -> IDREQ ri=54934 ai=127

*Mar  5 02:55:34.711: ISDN BR0 Q921: User TX -> IDREQ ri=16375 ai=127

Apparently the router is attempting to establish Layer 2, and is sending IDREQs to the ISDN switch in the CO, but the switch isn't responding. I've opened up another ticket with the Deutsche Telekom with the hope that I can solve this problem with them. Has anyone else experienced this?


An update: Yesterday morning I could make all kinds of isdn test calls, but then suddenly it started up with the IDREQ nonsense again, ending in the same error.

Do I need to replace the router a second time?


So I found the problem... It's a bug in the IOS software 15.1(3)t. I downgraded one of the routers to 12.4(6)T6 and it can now dial out just fine.

The problem here is that I upgraded the other router to 15.1(3)t because the customer wanted to upgrade the ADSL line to 16 Megabit ADSL2+, and 12.4(6)T6 contains an ADSL Modem firmware that's not compatible with ASDL2+ @ 16 Megabits, so now I need to find a way to downgrade the router's firmware while keeping the ADSL Modem firmware.


You can update ADSL firmware indipendently from IOS.


As far as I recall it's a link error. Do you have a green light flicking on slot. Can you ISP ring your router ? It could be a line error. If the line is OK, check your PI/VCI settings against your ISPs settings.

If that is Ok, check how you are authenticating.

If using chap, you should have the line > ppp authentication chap callin


please rate if it helps.