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PRI Circuit "Slave Timing"? 3

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dsm600rr

dsm600rr

IS-IT--Management
Nov 17, 2015
1,444
US
Hello all,

I have a customer with a Standard TDM PRI that we are routing all of their faxes through. The faxes are coming in/out with the text looking scrambled as if someone pulled the page out of the fax machine. This happens about a 1/3 of the way down the document.

Per the Carrier: they are seeing "Very Overt Timing Slips over the Circuit", and the "Equipment needs to be Slaved to the Timing that is being sent by Windstream".

Suggestions?

Thank you.
 
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primary clock for pri should be set to Network, 2nd PRI clocking needs to be set to fallback, what is yours set to ?
 
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joe2938: They have 3 PRI Circuits. They are all set to "Network". Two PRI's are set to Line Group 0, The TDM is set to Line Group 1 - Used for Faxes and spoofing.
 
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This is your problem then, set the other 2 pri's to fallback
 
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joe2938: Thank you. Can you help me understand why having them all set to "Network" is not good. Also, how would you determine what Circuit should be set to "Network"?

Thank you!
 
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because you can only have 1 clock timing source, think about it
 
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Doesn't matter as long as 1 is set to Network and the other 2 are set to Fallback
 
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joe2938: Quick question. Are you thinking these a Bonded T1's? I read somewhere that the IP office cannot share signaling channels across PRI's. Each one has to have its own Signaling Channel.
 
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well how many channels are active, on a bonded it will be more than 23 bearer channels
 
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You should select the PRI that will most likely provide the best clocking signal as Network. If you have several set as Network, the IP Office will (if I recall correctly) use whichever one is first in terms of port numbering.

Stuck in a never ending cycle of file copying.
 
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Few other things to note. One of the the PRI's is coming in over copper.
The other 2 PRI's are coming in over fiber, connected to a Cisco Router which emulates a PRI Connection and finally to the IPO
 
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Don't make people repeat themselves by second guessing them, winds people right up :)
 
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sizbut is 100% correct. you can have multiple sources set as Network and they are checked in order - it's even in the manual... Link (I think that the IP Office manuals are excellent reference docs, they are not so useful as self teaching books but they were clearly not designed for that)

The question of which source is best (so set as network) may need a bit of knowledge and experience but in this case it is the real copper trunk from the Exchange/CO.
Ideally you'd set the ones to the Cisco to Unsuitable and have it clock from the IP Office - but I doubt you'd be able to get that done, so set them as fallback.

Real trunks from the carrier over copper or fibre (with TDM NTU/CSU/DSU - NOT routers) are best. They have really good Network clocks and that's what you want to synch to.
Next is the same but microwave (yes, I've been doing this that long) - the clock is good but the transmission is prone to interruptions from trees, birds, storms, workers on the roof (yes really)
Then there's what you see more of these days is VoIP (SIP presumably) trunks delivered on fibre but converted from IP to TDM using a router (Cisco in this case) - that will use the internal clock source of the router (not a network clock source) but follow the convention and clock from the supplier if that's all you have, or use it as fallback.

Then there are the links to other PBX systems.. but that's a lesson for another day ;-)

Sometimes VoIP is easier!
 
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wow was always taught to only have 1 clocking source, who knew
 
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VoIP Numpty: Thank you for the great post. I set all of the trunks to "Fall Back" and the TDI PRI as "Network" with a Scheduled reboot for tonight. I will report back on the results.

amriddle01: That was not my intention.
 
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I just found out they now have Bonded PRI's, They most of did this when they switched one of them over to Fiber.
 
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