We have a new PRI thats giving a dead air effect. Telco has looped to the NIU and can send and receive echo's successfully. I can also send tone from our Router to the phone successfully. But when a call is made from phone to pstn, no voice traffic gets passed but call setup messaging occurs and the call can be connected. Basically I am questioning the cabling between the NIU and the router interface. Can wiring, either crossed over or incorrect pin out cause this? Can it cause the D channels to come up, but not pass voice traffic?
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Can PRI cabling cause Dead Air?
- Thread starter TelcoTech
- Start date
For the most part the answer is NO! If the DS1 wiring is wrong or defective it would not work and you would have lots of BERs and alarms of one kind or another.
I would check the alarm stack in your router or other attached equipment for errors or alarms.
When you place test calls do you get any voice path in either direction or just nothing??
You stated you can send tone from the router to the phone. What about to a BCH or from the phone to the router?
There is only one DCH, and 23 BCHs on a DS1 circuit provisioned as PRI ISDN.
What kind of equipment are you using?
....JIM....
I would check the alarm stack in your router or other attached equipment for errors or alarms.
When you place test calls do you get any voice path in either direction or just nothing??
You stated you can send tone from the router to the phone. What about to a BCH or from the phone to the router?
There is only one DCH, and 23 BCHs on a DS1 circuit provisioned as PRI ISDN.
What kind of equipment are you using?
....JIM....
strmwalker
Technical User
TelcoTech..yes cabling can cause the problem you are
asking about,SYQUEST think about it what type of circuit
are we talking about we still have transmit and recieve
ear to mouth that my two cents.
no problems only solutions
strmwalker
asking about,SYQUEST think about it what type of circuit
are we talking about we still have transmit and recieve
ear to mouth that my two cents.
no problems only solutions
strmwalker
In my 17 years as a C.O. tech, I can't think of any time where cabling caused 1-way audio and nothing else.
Usually suspect cable will cause other problems including Bit, CRC and possibly Frame errors.
Depending on which pair has the problem, the errors would be seen locally and would also be reported on the opposite end as "Far End _______" errors (at least that is how the T-Berd 224 reports them).
Usually suspect cable will cause other problems including Bit, CRC and possibly Frame errors.
Depending on which pair has the problem, the errors would be seen locally and would also be reported on the opposite end as "Far End _______" errors (at least that is how the T-Berd 224 reports them).
What kind of phone switch do you have? If it is a Norstar you may need to go onsite and manually reboot the card that has a yellow light. Had this happen when we a power outage at a site. Network was working fine, phones one way speech. Went on site reset the card 2 way speech re-established.
mikeydidit
IS-IT--Management
It is pretty easy these days to find a bad circuit. If they can loop it up and it test clear with no errors, it's going to be an equipment problem. Most of these I have seen have been in the cards at the CO. I have 1 DS1 pack go bad after being in service for 13 years and it was not the problem you are discribing.
Hell, there are no rules here - we're trying to accomplish something.
Thomas A. Edison
For the best response to a question, read faq690-6594
Hell, there are no rules here - we're trying to accomplish something.
Thomas A. Edison
For the best response to a question, read faq690-6594
- Thread starter
- #8
Here is an update of some more troubleshooting. First we are using Cisco IPT. The circuits go into a 3845 router. We put a hard loop on the router interface and the circuit shows up. We move the hard loop into the first patch panel and the circuit shows down and doesnt come up, BUT if we plug the patch cable back in from that same patch panel to the router interface it will show up again. Also we have no two way speech. The telco has confirmed speech to the NIU. And I have verified speech from router to phone. But there is no two communication getting end to end so it would appear that its stopping between the NIU and the router interface during the extension of the circuit.
HarrisD1200
Technical User
Not a help, but ideally, you'd get someone with a PRI tester on site. They could look both directions, and SHOULD be able to isolate the problem fairly quickly (especially if they can monitor). Knee jerk response to this is that the two sides are picking different B channels for whatever reason.
strmwalker
Technical User
Dexman...in my 35 years in the business starting outside
plant moving inside to toll test whare special curcuits
come from,then working in the central office moving back out to the field then work in the business marketing
side of the industry with rolm corperation and working on nortel pbx,i have seen a cable run a good man crazy because
he never seen or heard of a cable causing one-way conversation well the only thing he did was change the cable
because everything but the cable had been changed,and boom
problem fixed he had 40 years in the business never say never.
no problems only solutions
strmwalker
plant moving inside to toll test whare special curcuits
come from,then working in the central office moving back out to the field then work in the business marketing
side of the industry with rolm corperation and working on nortel pbx,i have seen a cable run a good man crazy because
he never seen or heard of a cable causing one-way conversation well the only thing he did was change the cable
because everything but the cable had been changed,and boom
problem fixed he had 40 years in the business never say never.
no problems only solutions
strmwalker
strmwalker,
I have yet to see it happen. Defective T1 cabling will manifest itself by causing carrier related issues. Now, inside cabling, that is a different story. However, when confronted with 1-way audio on an ISDN circuit, I would be more inclined to grab a protocol analyzer and trap "D" channel messages than knocking down the T1 for a test to the NIU (if so equipped) or the CSU unless one of the 2 ends is reporting carrier related issues.
Ultimately, our job is to provide the customer with the best service possible. How we achieve that goal varies, but it is what we all strive for.
I have yet to see it happen. Defective T1 cabling will manifest itself by causing carrier related issues. Now, inside cabling, that is a different story. However, when confronted with 1-way audio on an ISDN circuit, I would be more inclined to grab a protocol analyzer and trap "D" channel messages than knocking down the T1 for a test to the NIU (if so equipped) or the CSU unless one of the 2 ends is reporting carrier related issues.
Ultimately, our job is to provide the customer with the best service possible. How we achieve that goal varies, but it is what we all strive for.
TelcoTech,
Other than telling us what equipment you are using, do you have answers to the other questions I posted above?
What about the router to the NIU? Did the service provider do any CSU looping on the router?
These are basic steps to troubleshoot the problem, any results?
What about the config on the CISCO, I have seen threads on the CISCO Routers Forum in the past discussing one-way audio problems on telephony related configs...
*I'm with Dexman on this one!
....JIM....
Other than telling us what equipment you are using, do you have answers to the other questions I posted above?
What about the router to the NIU? Did the service provider do any CSU looping on the router?
These are basic steps to troubleshoot the problem, any results?
What about the config on the CISCO, I have seen threads on the CISCO Routers Forum in the past discussing one-way audio problems on telephony related configs...
*I'm with Dexman on this one!
....JIM....
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