Loud Ringback Noise

[underwod]

We are experiencing a problem with an analog line at one of our buildings. It is intermitant and only appears to be happening on the first line in the hunt group. Before an incoming call from the pstn hears a ringback, the caller hears a loud grinding noise. This noise can continue into the call being answered. It disappears after a few seconds. If we disconnect the line from the gateway and plug directly into an analog phone, we cannot duplicate the problem. Verizon has been out and can find no problem with the line. It is looking more and more like either a configuration or ios problem. The gateway is a cisco 1760 (h.323) running c1700-sv8y7-mz.124-15.T1.bin
We have another gateway running this same ios and it is not experiencing the problem.
Has anyone else seen this problem?

 

[pndscm]

I have not seen that problem but I would change the FXO card.

 

[whykap]

If you move the line to a different port does that follow the line? That is good way to isolate if it is a line issue or a hardware issue.

 

[underwod]

Yes, to both the responses. We swapped the FXO card and moved the port. It followed the line. It is the first line in the hunt group and so gets hit the most. The second line gets a tiny bit of the noise but, just for a split second. The third line in the hunt group doesn't get it at all. All the lines/ports are set up identically on the router.
Thanks,

 

[loucanick]

Sounds like a telco problem. If you can plug a phone into the line and not get any noise, and the noise follows the line, all the arrows are pointing back to the telco.

 

[whykap]

I agree as well. If the problem follows the line it is the line. Either a ring voltage issue or something along those lines. Have Telco come out with a voltage meter and test it.