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CO Line lights up but does not ring

Derek Thom


We have a customers UC520 that lights up the CO Line when a call is coming in, but it is a solid red light (doesn't flash). This lasts for about 10 seconds, and then it goes dark, lights up again, and then rings like it normally should (and the corresponding button flashes). If no one picks up then it goes to voicemail as normal. Also, if the line is picked up while just solid red, it does connect the call just fine. According to the customer this happened abruptly one day, and is only on the first CO Line (they have 12 total).

The system was configured completely with CCA 3.0 and is running software pack 8.0.1. I checked under CCA to make sure the right CO Line was there, and everything looks fine. I tried deleting the button and readding it on a phone, but the same issue occurs.

Any thoughts as to why this is happening?



1 Accepted Solution

Accepted Solutions

David Trad
Rising star
Rising star

Hi Derek,

I don't suppose you can debug that voice port can you?

I have seen this issue before, and it turned out that the port it was plugged into went the way of the dodo birds so TAC RMAéd the system and problem went away

But that would be the simple solution to the problem, the harder one is where you debug it and everything looks find and then you start conducting bizarre and insane tests to diag the problem, only to end back at the original proposed point of swapping the system out

You can debug it now, or you can log a support request doing that now will save you many days of headaches and you will also be doing the right thing by the customer.

Just a thought



Cheers, David Trad. **When you rate a persons post, you are indicating a thank you or that it helped, but at the same time you are also helping to maintain the community spirit - You don't have to rate posts and you wont be looked down upon :) *

View solution in original post

7 Replies 7

Ryan Hardy

Have you made an outbound call on that line?  I had a wierd issue like this before where the phone would ring for a second, then stop, and start again, but i could never answer the call.  Turned out, I had miss-punched my 1 pair and only 1 wire was going to pins 4 and 5.  So you dont need both wires to make a phone ring, but you will need the whole pair to answer the call and make a call.

I'm sure this is way off, but you never know.  Sounds like what happened to me back in the day.