Hi everyone,

I'm having this very strange issue on one particular extension. All other phones are working just fine on the same floor.

Both the SLT and the proprietary phone are connected to the same jack on different pairs.

The issue is that on a single line telephone (2554 set), the phone will not ring. There is a constant, steadily repeating beeping noise on the phone along with another set of loud buzzing and humming noises mixed in there too. In addition, the dial tone is quite soft compared to other telephones attached to other jacks. The phone will not ring at this jack but it will if I plug it directly into the PBX, probably due to excessively low voltage at the plug.

On a proprietary telephone (KX-T7433), the phone works fine except recently if I have a second call coming in there is a loud very quickly repeating clicking noise (in the same pattern as the ring comes in ,maybe 20 hertz) in the receiver which does not occur if it is attached directly to the PBX using a short line cord to the same port. I tried a second phone and it exhibits the same issue at the jack, which rules out the phone or the port being bad.

I tried attaching an EMI filter to the jack but it doesn't help. I also attached the grounding lug on the PBX to ground (it was previously not attached) but the problem remains. I just replaced the jack at the phone end and there is no difference.

Could someone lead me in the right direction? Is there induced electrical voltage or should the wiring be investigated, and where?

Thanks!

Sounds like the wiring. If you swap that jack to a different extension on that floor is it the same problem?

You were right, I had a look and it turns out that one of the cables in between patch panels was bad, going to replace them today.

Thanks!