My wired phone answers by it self. - Page 1
Forum section: electronics / general

author: vlad777
author_rank: Frequent Contributor
timestamp: February 11, 2019, 05:35:52 pm
content: My wired phone answers by it self.I tried lots of combinations of two wired phones and connectors I got, to try to diagnose the problem.In the end I disconnected everything , called my self using a cell phoneand after ringing several times , connection was established.Can somebody tell me how is this possible?What needs to be broken to have this effect?Many thanks.

author: German_EE
author_rank: Super Contributor
timestamp: February 11, 2019, 05:40:55 pm
content: Easy, the government organization tapping your phone answered the call on your behalf

author: vlad777
author_rank: Frequent Contributor
timestamp: February 11, 2019, 05:49:41 pm
content: Let's not go there yet (It's never aliens)I am thinking of a malfunction that would produce this behavior.I think that the oldest systems use to short circuit the wires to produce a pulse.So maybe a short somewhere is misinterpreted.

author: ebastler
author_rank: Super Contributor
timestamp: February 11, 2019, 05:50:47 pm
content: Mechanical bell ringing so hard that a loose contact gets opened or closed?

author: vlad777
author_rank: Frequent Contributor
timestamp: February 11, 2019, 05:54:02 pm
content: I don't have mechanical bells , I don't know what the telecom has but i doubt it is mechanical.

author: tsman
author_rank: Frequent Contributor
timestamp: February 11, 2019, 06:07:59 pm
content: You've got a ring trip fault. Moisture has entered a cable/junction somewhere and created a diode junction or you've got a bad connection somewhere. Check your wiring + sockets from the demarcation point onwards. If it is easy to do then temporarily disconnect all your extension wiring from the demarc point to see if that affects it. If everything is good then you'll need to talk to your telco and get them to check their side.

author: vlad777
author_rank: Frequent Contributor
timestamp: February 11, 2019, 06:16:08 pm
content: Thanks!"A diode junction". How does that work?

author: tsman
author_rank: Frequent Contributor
timestamp: February 11, 2019, 06:28:23 pm
content: Quote from: vlad777 on February 11, 2019, 06:16:08 pmIt is because of corrosion or contamination in the socket etc... which creates a very crude PN junction from the oxide formed. The AC ringing voltage gets rectified by this and the exchange thinks it has gone off hook because of the DC current flow.Check your wiring. It is usually something on your side that has gone bad.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: February 11, 2019, 06:36:43 pm
content: Could you please give some more info about your phone setup?Such as: type of telephone (electromechanical, electronic with additional functions...)Also switches, wiring, PABX?Type of service/telephone line (basic analog or coming out of a DSL box?)When the telephone 'answers', which signal path is established? What do you hear?Possible would be the erroneous/unwanted activation of a build-in answering machine function.Also many possible other reasons, so we need more info.

author: vlad777
author_rank: Frequent Contributor
timestamp: February 11, 2019, 06:54:58 pm
content: electronicno PABXbasic analogno answering machineI hear just ringing then silence.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: February 11, 2019, 07:08:49 pm
content: Could still be a unconfigured voicebox activating after a update error of the Telco equipment.

author: Red Squirrel
author_rank: Super Contributor
timestamp: February 11, 2019, 07:41:42 pm
content: Call 611 repair and see if they can run a line test. Will show any resistance etc. Call with your cell and not that line. Odd time of year for water to get into a line as everything is frozen solid, but I've seen stranger things. This time of year it's fibre cuts because of snow plows, and dump trucks that forget to lower their box.

author: ogden
author_rank: Super Contributor
timestamp: February 11, 2019, 07:56:55 pm
content: Quote from: vlad777 on February 11, 2019, 06:54:58 pmI would not bother. Call your telco and ask them to fix it. After all you are paying for that line and it is broken now.

author: floobydust
author_rank: Super Contributor
timestamp: February 11, 2019, 07:58:46 pm
content: This happens when the ringer capacitor has failed. Usually a lightning transient.I have an old Western Electric 500 that answers after a ring or two.The capacitor's purpose is to block any DC to the ringer/bell, and to help the bell resonate at 20Hz.Look for a big film capacitor in the phone, like 0.47-1uF 250VAC or higher, and replace it.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: February 11, 2019, 08:46:31 pm
content: Quote from: floobydust on February 11, 2019, 07:58:46 pmunlikely, when he says that he has disconnected everything. I understood that such, that NO terminal device is connected to the line and it still happens.Another thing to find out to help the telco search in the right place would be whether your cell phone (or another subscriber) really sees the 'connection established' signalisation. (display on cell or billing counter pulse on a analogue line)

author: floobydust
author_rank: Super Contributor
timestamp: February 12, 2019, 12:45:49 am
content: For this thread, it was water and corrosion:https://www.eevblog.com/forum/chat/estimating-line-r-in-a-twisted-pair-telephone-line/msg1935973/#msg1935973An old story, a Telco guy came out and the old lady told him the phone was not working.Telco guy makes it ring and her dog started barking and yelping. Turns out the old lady chained the dog outside to the phone lead in cable. The insulation wore off so the dog got zapped everytime the phone rang. Ouch.