bri incoming call problem

Unanswered Question
Oct 9th, 2007

i have a problem that my bri layer 1 is deactivated after 30 seconds of idle

so the first incoming call don't receive on ny extension

interface BRI0/0/0

no ip address

isdn switch-type basic-net3

isdn tei-negotiation preserve

isdn point-to-point-setup

isdn incoming-voice voice

isdn sending-complete

trunk-group ISDN-BRI 1

I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Paolo Bevilacqua Tue, 10/09/2007 - 06:51


this is normal, the switch deactivates the line after 30 secs inactivity.

Notwithstanding, you still should receive all calls in a regular manner.

I suggest you configure "isdn tei-negotiation preserve", and check again.

mostafamossad Wed, 10/10/2007 - 01:21

i did that command but there is no result

please anser me as fast as u can

till now the incoming call not recieved by my reception

the strange thing is that if the nt1 connected to analog phone it received direct

but when i connect it to the router the problem appear

please send me a sample of configuration

and i forward the incoming call to the reception using connection plar under voice port is that right

Paolo Bevilacqua Wed, 10/10/2007 - 01:34


there is no special configuration beside "isdn tei-negotiation preserve" on BRI ports. The router should able to receive the call immediately following re-activation by PSTN.

Which IOS are you running ? Can you upgrade to 12.4(11)XJ4 and try again?

Failing that you would need to provide output of "term mon" and "debug bri" and "debug isdn q921".

Paolo Bevilacqua Wed, 10/10/2007 - 04:04

No, cptone doesn't really applies to BRI ports.

Please send again configuration and output of "term mon", "debug bri", and "debug isdn q921".

Paolo Bevilacqua Wed, 10/10/2007 - 06:36


I see multiple TEI are used on the bus. Do you have any other device on it ?

Please remove "isdn tei-negotiation first-call". Save conf and reload router.

If problem persist, please take again the debugs all enabled at the same time, also enable "debug isdn q931". Make a call from outside when layer1 is deactivated. If the first call doesn't succeed, make a second one.

Post the output here.

mostafamossad Wed, 10/10/2007 - 07:52

i attached for the output of the debug as u wanted

i am using ios 12.4(11)xj4 due thing this problem may be related to the ios version

and there is something strange sometimes even when the isdn link is deactivated the incoming call success and i can receive it but in most cases the incoming call don't success

Paolo Bevilacqua Wed, 10/10/2007 - 09:41

There are few strange things in the trace.

First, layer1 is initially activated by the switch, this is successful and is not further deactivated.

Then a call release on timer expiry is seen. The call had to be active before beginning of the trace, and it should cause timers to expire.

Then it is seen that the switch probes for TEIs that router is not using. Have you rebooted the router? Are there other devices on this BRI ?

Then the call comes, was it the first or subsequent try ?

Finally the switch reject an apparently valid alerting message sent by router, but this is not influencing and is ofteen seen.

Worst case it can be a problem of compatibility with the switch, but I would like to understand, how the timers are expiring in first place.

mostafamossad Wed, 10/10/2007 - 11:46

thdebug output was for 2 tries to place acall

in first try i didn't recieve the call but layer1 and layer2 became active

then i made second call while it is still active te call is received normaal

and now i don't know what the steps that i should take

Paolo Bevilacqua Wed, 10/10/2007 - 11:56

hi mostafa, I was asking if you have devices on the BRI bus and if you have reloaded router and the NT1.

On the other hand it may be an issue with the service because the first call never appeared on the bus, in fact if you was to monitor all calls that are presented to to router, there is an increasing ID in the setup message and you should check if that get incremented or it skips a sequence when for the missed call.

When telco is serious about these problem they have to come onsite with and ISDN BRI analyzer (like DA-30, but there are many models) and be able to see that the bus is activated and the call is presented.

Anyway, what do you hear as a caller when it doesn't go through ?

mostafamossad Thu, 10/11/2007 - 03:00

there are strange thing whr the switsh reply me with 2 different tei u can see that in the configuration


This Discussion