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RKM
Aspiring Expert
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Message 1 of 8

Is there any point in putting a phone on a landline these days?

I need a BT landline to get an Internet connection however, given the amount of junk/scam calls we get on it, I am considering disconnecting the phone completely!

We use BT Call Protect on the line and I just looked at the data:

1. 40 blacklisted numbers

436 calls sent to junk voicemail in the past 30 days

Last 20 calls received in previous 20 days

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Keith_Beddoe
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Message 2 of 8

Re: Is there any point in putting a phone on a landline these days?

Why do you need phone connected to your line?

If the phone line is noisy or has a high resistance connection, then that will affect your broadband.

The lack of any current flowing through the wires due to the lack of a phone providing an occasional loop, causes oxidisation at any joints which causes the line resistance to increase. This does not show up on a normal line test.

With Private Circuits it is common practice to allow a small "DC Wetting" current to flow through the line to prevent this problem.

https://en.wikipedia.org/wiki/Wetting_current

There are quite a few people that do not plug a house phone in to check dial tone every so often. This can cause issues with broadband. Also, if one wire has become disconnected (quite common), then that will cause no broadband,  constant disconnections, or a very low speed.

The answer is to plug your phone in occasionally, and ring it, that helps to keep the connection clean.

There is another way of maintaining a "wetting" current which I use, as well as having a phone plugged in (I do not get scam calls), that involves a high value resistor connected across the line.

I am on ADSL and had occasional issues with high resistance connections.

gg30340
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Message 3 of 8

Re: Is there any point in putting a phone on a landline these days?

If you don't make or receive phone calls other than junk calls just switch the phone to silent if it has that option. That will prevent you from hearing and wasting your time with the calls but will still allow your line to be active and prevent the problem that Keith has outlined. It also allows you to use the phone in an emergency should you need it.

Keith_Beddoe
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Message 4 of 8

Re: Is there any point in putting a phone on a landline these days?


@gg30340 wrote:

If you don't make or receive phone calls other than junk calls just switch the phone to silent if it has that option. That will prevent you from hearing and wasting your time with the calls but will still allow your line to be active and prevent the problem that Keith has outlined. It also allows you to use the phone in an emergency should you need it.


As an extra advantage, the incoming calls that you will not hear, will help to keep any high resistance connectons at bay, as the 80 Volt AC ringing supply, is very effective at clearing faults.

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licquorice
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Message 5 of 8

Re: Is there any point in putting a phone on a landline these days?


@Keith_Beddoe wrote:


As an extra advantage, the incoming calls that you will not hear, will help to keep any high resistance connectons at bay, as the 80 Volt AC ringing supply, is very effective at clearing faults.


That will still happen regardless of whether a phone is connected or not.

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Keith_Beddoe
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Message 6 of 8

Re: Is there any point in putting a phone on a landline these days?


@licquorice wrote:

@Keith_Beddoe wrote:


As an extra advantage, the incoming calls that you will not hear, will help to keep any high resistance connectons at bay, as the 80 Volt AC ringing supply, is very effective at clearing faults.


That will still happen regardless of whether a phone is connected or not.


But there would normally be a path through the phone, even if the ringer is silenced, as it purely an electronic ringer which would not be passing the full current anyway, and is usually just a repeater, not like in the days of mechanical bells in the 706 telephone.

Most modern phone allow you to play different ringtones, which bear no relationship to the incoming ringing pattern, and are generated by separate circuitry.

I suppose in practice, it will not make much difference.

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licquorice
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Message 7 of 8

Re: Is there any point in putting a phone on a landline these days?

The path will be through the capacitor in the master socket, that's why its there, to emulate a bell circuit.

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Keith_Beddoe
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Message 8 of 8

Re: Is there any point in putting a phone on a landline these days?


@licquorice wrote:

The path will be through the capacitor in the master socket, that's why its there, to emulate a bell circuit.


Actually, the default path is via a capacitor and a high value resistor. This creates a time constant which is used by the Line Test System to determine the presence of the NTE.

master circuitry.jpg

If a phone is plugged in, then the path is also via the phone bell circuity as well, and gives a slightly different reading.

On the old phones it was possible to use the  "test desk" equipment to reverse the voltage and see a large capacitance "kick" on the meter if a phone was plugged in, and a much smaller one if it was just an NTE.

Some of the experienced "Trunk Test" people in the exchange, could actually tell whether it was just cable capacitance, or an NTE on the end.

That was a long time ago now, "Trunk Test" is long gone Smiley Wink

There were still test desks in the exchanges, last time I was there, but many no longer worked.

Anyway, getting off topic now.

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