We get this problem occasionally -- I wondered if anyone had seen similar before I start monkeying around with our equipment.
We have 3 DECT phones on one base station. This affects the first phone (used just a couple of metres from the base). The others haven't been used enough to know for certain if it affects those too.
What happens is we'll push the 'off-hook' button to get a dialtone. Immediately, over the top of the dialtone we can hear a regular, loud click. It's about 1 click-per-second -- and is a 'loud' click. If we make a call, the other party can also hear the click. Sometimes, we won't be able to hear the click, but the other end can. And sometimes the click isn't immediately present, but starts during a call.
Out of about 10 calls per week, this might happen once or twice. And it's not something which hanging up and redialling fixes -- it disappears on its own after a time.
My MyDSLWebStats shows no affect on our VDSL2 service - no SNRM changes or resyncs.
Due to the regularity of the clicks, but intermittent nature of the problem, I'm wondering: Presumably, DECT does some kind of frequency hopping. Could it be that we get this noise when DECT picks a frequency that's being interfered with by our WiFi? We have an 802.11ac/n router sat not far from the base station.