questions about PRI voice on UC520

Unanswered Question
Jul 15th, 2008
User Badges:

I will be setting up my first PRI in a couple of days and figured I need to do some homework before I jump in. Below I have the config that I want to start off with and a couple of questions: Thanks in advance.

1) Based on the config below, do I need any more commands to bring up the circuit?

2) I asked my provider to provision for NI Version 2 but I don't seem to have that option when configuring the circuit. Should I ask them to reprovision to NI Version 1?

3) I figure that at some point in the bring-up of the circuit the telco tech will claim that "everything is fine on my end, must be your end". What are some good debug or show commands that will help to troubleshoot the circuit if it doesn't come up?

card type t1 0 3


network-clock-participate wic 3

network-clock-select 1 T1 0/3/0


isdn switch-type primary-ni


controller T1 0/3/0

framing esf

linecode b8zs

pri-group timeslots 1-24


interface Serial0/3/0:23

no ip address

encapsulation hdlc

isdn switch-type primary-ni

isdn incoming-voice voice

no cdp enable


voice-port 0/3/0:23


  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 4.5 (4 ratings)
Ayodeji Okanlawon Tue, 07/15/2008 - 04:34
User Badges:
  • Super Bronze, 10000 points or more
  • Cisco Designated VIP,

    2017 IP Telephony

One thing I learnt from my senior friend here Paolo, is to use the loopback command on your controller...This way you can authoritatively inform the telco that your end is use the loopback command do the following:

1. conf t

2. controller t1 0/3/0

3.loopback local line

Exit the config mode and type sh controller t1 0/3/0, you should see up up and looped.

Coommon and most helpful commands used to troubleshoot isdn setup are

1. debug isdn q.921 ..if your layer 2 is not coming up, this will help you to see message exchanges between your t1 card and the telco switch

2. Use show isdn status, to see the status of your isdn cirtcuit, this will show layer1 to layer 3 status..ideally if evrything is good, you should see multiple frame established..similar to this

ksh1f-intr3825#sh isdn status

Global ISDN Switchtype = primary-net5

ISDN Serial1/0/0:15 interface

dsl 0, interface ISDN Switchtype = primary-net5

Layer 1 Status:


Layer 2 Status:


Layer 3 Status:

1 Active Layer 3 Call(s)

CCB:callid=479A, sapi=0, ces=0, B-chan=1, calltype=VOICE

Active dsl 0 CCBs = 1

The Free Channel Mask: 0x80007FFE

Number of L2 Discards = 0, L2 Session ID = 4

Total Allocated ISDN CCBs = 1


3. You can use a show controller t1 0/3/0 to see if there are any alarms on your circuit..The type of alarm will tell you where the problem is.

Attached is a glossary of isdn alarms and what they mean.

4. You might need to add this command under your

interface Serial0/3/0:23

isdn bchan-number-order ascending.

This is used to avoid a term called glare condition..basically this happen when your telco and router select channels in same order.

5. ALso on your pots dial-peer you will need to add

progress_ind alert enable 8

eg dial-p 1 voice pots

progress_ind alert enable 8

This will let your users hear phone ringing before the called party picksup.

This is all I can think of now...

DIEGO ALONSO Wed, 07/16/2008 - 11:34
User Badges:

Hello again. I brought the PRI up today and was able to make outbound calls quite easily. However inbound calls I cannot get to work. I did "debug isdn q931" and I can see the 10 digit inbound call. However I cannot get an ephone-dn to receive the call. My DNs currently look like this:


ephone-dn 91 dual-line

number 4085551212

label 408551212

description DID1

name DID

call-forward busy 200

call-forward noan 200 timeout 10


Any idea?



paolo bevilacqua Wed, 07/16/2008 - 12:14
User Badges:
  • Super Gold, 25000 points or more
  • Hall of Fame,

    Founding Member


it's a bit strange because when the number matches, phone must ring.

Anyway, configure a translation-profile and rule:

voice translation-rule 100

rule 1 /^40855511/ /2/

voice translation-profile makedid

translate called 100

voice-port x/y/z

translation-profile incoming makedid

and give you DN regular extension numbers like 2xx.

You should be ok then. The example is if you have 2 actual DID digits.

DIEGO ALONSO Wed, 07/16/2008 - 12:49
User Badges:

Don't know if it would have anything to do with this but I noticed that the PRI was provisioned for Natl ISDN 2. However I don't see a Natl ISDN 2 option for switch type. I have:

isdn switch-type primary-ni

interface Serial0/3/0:23

isdn switch-type primary-ni

How do I know I am using Natl 2? I am able to make outgoing calls.


paolo bevilacqua Wed, 07/16/2008 - 12:52
User Badges:
  • Super Gold, 25000 points or more
  • Hall of Fame,

    Founding Member


switch-type doesn't really matter, beside ni-1 and 2 are highly interoperable.

All what matter are the numbers. Get them right and everything works, a small mistake and nothing does.

DIEGO ALONSO Tue, 07/15/2008 - 05:22
User Badges:

Thanks guys. Those tips/docs look like they are going to help a lot.



This Discussion