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Old 16th Nov 2020, 1:29 pm   #1
BigClick
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Default Virgin Media and old phones

Does anyone know what the current draw limits / parameters for connecting telephone instruments to a Virgin hub are? The Virgin hub uses VoIP.from the hub to the exchange.

I have a compact (tele 776) that works fine. However, my "Button A Button B" payphone which was working perfectly on an analogue BT land line will not work with the Virgin hub.

I get dial tone initially but if its put on hook I can't get dial tone again.

I do hear the dial tone extremely quietly even when its on hook (with my finger) that eventually changes to the equipment engaged tone.

I have to do a hard disconnect of the line to start the dial tone again.

I have a feeling even when on-hook it is signalling the hub as off-hook?

Maybe there is a mod I can do to stop this?
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Old 16th Nov 2020, 2:06 pm   #2
OscarFoxtrot
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Default Re: Virgin Media and old phones

Sky's analogue line spec (BT's SIN should be similar, but I can't find it as quickly)

The interface will recognize a loop resistance of greater than 10 k Ω between the ‘A’ and ‘B’ wires as an off-line (on-hook) condition. A current of less than 3.5mA will not be recognized as a seize condition

The interface will recognize a loop resistance of less than 1 k Ω between the ‘A’ and ‘B’ wires as a seize condition. A current of 10mA will be recognized as a seize condition.


So if you can put a DC ammeter in series with your payphone and measure the line current on- and off-hook.

If it's within the above limits I would suggest to Virgin that their box is not providing an analogue line within specification, unless they publish their own interface specification which is different.

I would also wonder whether your 2-wire Virgin hub connection is correctly converting to a 4-wire BT connection, in particular the earth on payphones was used for signalling to the exchange (for emergency calls in manual areas without inserting the fourpence first) and this might be causing a partial short across the line.
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Old 16th Nov 2020, 4:22 pm   #3
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Default Re: Virgin Media and old phones

Thank you OF. I will measure as advised.

Not sure what you mean regarding the earth signalling? This unit definitely worked as a two wire "Loop-Dis" in the past.

I believe the dial was customised on Button AB payphones to allow a 9 or 0 without having to put any pennies in the slot.

I am prepared to be educated on it though
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Old 16th Nov 2020, 5:50 pm   #4
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Default Re: Virgin Media and old phones

On manual exchanges the caller could press a button to call the operator in emergency. Ordinarily the caller had to put in his fourpennies and then the phone went on-hook and the operator answered.
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Old 16th Nov 2020, 7:36 pm   #5
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Default Re: Virgin Media and old phones

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Originally Posted by BigClick View Post
Thank you OF. I will measure as advised.

Not sure what you mean regarding the earth signalling? This unit definitely worked as a two wire "Loop-Dis" in the past.

I believe the dial was customised on Button AB payphones to allow a 9 or 0 without having to put any pennies in the slot.

I am prepared to be educated on it though
The earth was only required for 'Emergency Call' signalling on A/B boxes working to a Central Battery manual exchange. Not needed on Central Battery Signalling manual exchanges but doesn't apply on automatic exchanges (except on a few remote 'Island Automatic Exchanges' in the remote islands off the NW of Scotland and the Orkney & Shetland Islands.

Just tried one of my A/B renters boxes on a Grandstream HT701 and a Grandstream HT818 and works fine on both for incoming/outgoing calls on the Collectors Network (CNet) that uses VoIP. The original GPO circuit of an 'automatic' A/B box installation is virtually identical to a Telephone 232 but with as you say the different coinbox dial. The electrical side is the same so hould work. Have you tried the A/B box on a 'BT' copper line since trying it on the VoIP?

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Old 16th Nov 2020, 10:41 pm   #6
bigfathairyvika
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Default Re: Virgin Media and old phones

Problem here also with a Virgin Hub 3.0
Old analog phone worked perfectly fine with the original wire line supplied by Virgin, but the Virgin Hub 3.0 uses its own idea of a phone line to convert into internet calling and you just get a horrible very loud buzzing on lifting the receiver.

I contacted Virgin with regards to this and they hadn't a clue apart from to say I should use a modern phone.

Mark
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Old 17th Nov 2020, 6:22 pm   #7
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Default Re: Virgin Media and old phones

I feel for you Mark. Sounds a bit different o my issue but could be related I suppose
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Old 17th Nov 2020, 6:39 pm   #8
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Default Re: Virgin Media and old phones

One thing I have noticed about ATAs and routers with telephone ports, is that there isn't as much ringing current available, compared to a genuine exchange line, so the usual "REN 4" guidance may not apply.
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Old 17th Nov 2020, 7:16 pm   #9
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Default Re: Virgin Media and old phones

Mark, tell us more about this "Old analog phone" what is it? For example, early GPO 700 series phones had a regulator board that could be bypassed, which might help.
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Old 21st Nov 2020, 4:27 pm   #10
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Default Re: Virgin Media and old phones

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Originally Posted by rambo1152 View Post
One thing I have noticed about ATAs and routers with telephone ports, is that there isn't as much ringing current available, compared to a genuine exchange line, so the usual "REN 4" guidance may not apply.
My Linksys PAP2NT is supposed to have a REN of five. It's currently connected to one 4000Ω and one 1000Ω bell and all is well.
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Old 22nd Nov 2020, 1:42 pm   #11
Oldcodger
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Default Re: Virgin Media and old phones

Quote:
Originally Posted by BigClick View Post
Thank you OF. I will measure as advised.

Not sure what you mean regarding the earth signalling? This unit definitely worked as a two wire "Loop-Dis" in the past.

I believe the dial was customised on Button AB payphones to allow a 9 or 0 without having to put any pennies in the slot.

I am prepared to be educated on it though
Earth signalling is where an earth on one leg of the line ( can't remember which as I could never see the fascination with Auto) to (on manual) called the operator or on Auto seized a switch. A lot of the older BT pabx systems used this .
One of the jobs I got involved with was checking the MDF records on our old CB manual board prior to change over to auto. Simple job- put a linesman tele across a pair and wait for operator reply. If no answer we simply put an earth on one leg. Soon found out that on an old call box, one leg earthed came up as normal call whilst the other leg showed up as an emergency.
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Old 22nd Nov 2020, 2:00 pm   #12
Dave Moll
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Default Re: Virgin Media and old phones

Earth recall is normally the B leg, so presumably the same here.
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Old 24th Nov 2020, 1:51 am   #13
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Default Re: Virgin Media and old phones

Most possibly, Dave, but in my days of hawking out old BT earth calling systems ,I stuck a tele on the line and if no DT, just tried an earth on one leg. Then it was call BT and ask for the line(s) to be made loop dis.
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Old 25th Nov 2020, 12:54 am   #14
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Default Re: Virgin Media and old phones

Quote:
Originally Posted by Oldcodger View Post
Most possibly, Dave, but in my days of hawking out old BT earth calling systems ,I stuck a tele on the line and if no DT, just tried an earth on one leg. Then it was call BT and ask for the line(s) to be made loop dis.
My working in telecoms was as a third-party maintainer in the early '90s, not long after deregulation. I came across a fair few earth-start lines, on PABX's that could equally have been configured as loop or earth start.

Our training, such as it was, did not include such eccentricities, and I think some of my colleagues might have condemned the lines as being dead.

As for myself, I probably drew on my childhood experiments with our party-line at home and guessed what was going on, particularly the distinctive "Bzzz" I heard in my test butt when the line was seized.

I wonder how long earth start lines were supported? I remember when meter pulses stopped being supplied.
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