
Ask HN: Why landline make crazy noise while hung up? - speeder
I decided to ask it here because the problem to me at least is so novel that I found it curious and interesting (although I still need to fix it...)<p>Basically, one of my landline phones on the company decided to make ear-splitting loud noises... but only while the phone is not in use, when you pick the receiver up the noises stop.<p>I have no clue what could do that, I didn&#x27;t knew a phone could be that loud (you can hear it across the room!) neither that it could make sounds while not in use.
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paulrpotts
If the phone is accidentally left off the hook (or if there is an electrical
problem with the wiring so that it is _reading_ as off the hook), the exchange
may drive it with a very loud fast BEEP-BEEP-BEEP-BEEP sound. That's just part
of how POTS (plain old telephone service) lines work. Traditionally a user
would not want to leave the phone off the hook accidentally, because then that
line could not receive calls, and if it was a party line, no one else on the
line could receive calls or make calls.

If it stays off-hook long enough, eventually this will go silent.

See: [https://en.wikipedia.org/wiki/Off-
hook_tone](https://en.wikipedia.org/wiki/Off-hook_tone)

And:
[https://en.wikipedia.org/wiki/Permanent_signal](https://en.wikipedia.org/wiki/Permanent_signal)

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simonblack
Faulty hang-up connections. Even when the phone 'looks' hung-up, it isn't. Fix
the hang-up buttons so that they work properly, or replace the faulty phone.

You'll very likely find that when you listen to the phone, and work the hang-
up buttons with your fingers, that the phone doesn't actually hang-up.

