PABX wiring issue


I have an ageing panasonic PABX that is capable of feedi9ng either straight POTS or digital p[hones.
To feed a POTS its uses two wire extenbsion cabling and a master socket with ring cap.
To feed digital phones it uses 4 wires.
Ive now acquired a bargian bundle of panasonic digital phones for it, but of course they don't currently work.
My question is this: is it possible to wire the BT sockets so as to be able to accept either phone? The signal wires are identical, the digital just adds two more wires to the other two terminals BUT one of those has the ring cap on it currently.
Its probably not a disater if I have to cut those out...but it would be nice to be able to plug either phone in and have it work.
Do modern phones need the ring cap?
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On Friday, 5 October 2018 09:48:44 UTC+1, The Natural Philosopher wrote:

No
John
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On Fri, 5 Oct 2018 02:16:44 -0700 (PDT), snipped-for-privacy@gmail.com wrote:

;-)
In the old days, all the handsets (master / extensions) were wired in parallel and the bells in series (with the ringing cap in the master phone) with a pair of contacts in the dial to disconnect (or short?) the bell circuit as you loop disconnect dial to prevent bell tinkle.
http://www.telephonesuk.co.uk/images/small/746_image1a.jpg
With the advent of multi frequency dialling, you didn't have bell tinkle so they often put the ringing cap in the handset in parallel with the main pair and then also in the BT box.
I feel I have been very lucky in my life / career as I worked for BT when we went from wired to plug in phones (and lots of people were having issues with their phones and extensions), then being interested in computers myself I was in a good position to deal with them commercially and for friends and family, along with dial-up modems (again, I was repairing 300 baud modems with BT when they were as big as a desktop PC). Then it was WiFi that was a bit of a black art and again, I was often called in to sort 'problems', typically with inter-compatibility. There was also the early uptake of ADSL and generic routers that needed a bit of configuration.
Then, as an opportunity of giving some of that back, IT training for 7 years. I would still rather do a 24 hour shift building, installing, wiring a load of LAN / WAN cabinets than an 8 hour day training, because it was such draining work.
Only ever really considered myself a 'Jack of all (well, many) trades' but then that suits my nature and seemed to also suit my friends and family. ;-)
Back OT, our 1x5 PABX can support LD and MF dialling and has a std BT (master) socket on the end of each extension. We do still have one LD phone (on a very old Telephone Alarm Clock Radio) but because it's on it's own line, don't have any bell tinkle or ringing issues.
Cheers, T i m
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On 05/10/2018 11:06, T i m wrote:

When I had four teenage kids living at home I put in a (recycled) PABX and, in the end, a second phone line exclusively for the kids. The mobile phone generation just don't know how lucky they are.
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On Fri, 5 Oct 2018 15:34:43 +0100, newshound

I did similar ... first the PABX (to stop people interrupting my modem downloads) and then the second line for data as I think I got it cheaper (and the kids fought for the other line though the PABX). ;-)

When we got our first mobile phone (Mercury M300 on One 2 One) I think I remember it coming with free local calls, evenings and weekends.
Come 6pm the kids would come and get the mobile and only re-appear for replacement batteries from the charger. ;-)
Cheers, T i m
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On 05/10/2018 16:01, T i m wrote:

My first mobile was on Orange (a Motorola MR20 IIRC) and came with a grand total of 15 minutes per month in the contract!
And the standard battery lasted about 8 hours on standby, while the extended one (twice as thick) lasted about 15!
SteveW
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On Fri, 5 Oct 2018 22:04:37 +0100, Steve Walker

And I bet you made them last. You weren't walking along (appearing to be ) talking to yourself? ;-)

I was going to say it's amazing how such things have progressed bit I'm not sure they have, not really?
The problem is, rather than using the improved battery technology to allow a phone to stay charged for a month, we improve the performance and features to a point where we consume the battery in 8 hours still. ;-(
Cheers, T i m
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On 06/10/2018 00:29, T i m wrote:

I'm glad to say that my five year old phone (I must upgrade soon as the memory is getting a bit limiting) allows me to make calls, use apps, browse the web, etc. and still gets 24 hours out of a charge.
SteveW
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On Friday, 5 October 2018 09:48:44 UTC+1, The Natural Philosopher wrote:

Possibly. The problem is that a 3-wire phone (as well as needing the ring cap in a master socket) will cause a short between the data wire on 3 and the B line wire on 5.
I've used LJ4 sockets, cut out the bell capacitor and out of circuit resistor on the proprietary phone, so I can use either a proprietary phone or a standard phone (or both in parallel) on a KX-TA system.
http://wiki.diyfaq.org.uk/index.php/File:Capture-Pana-wiring-UK.JPG
The latest version "digital" keyphones won't work on the older version "hybrid" systems so that might also be the problem
Owain
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On 05/10/18 12:11, snipped-for-privacy@gowanhill.com wrote:

Thanks m8. Its a pana KX-TA 64 pabx and the phones are 7750s and a 7730 I think.
Its prolly no big deal if I cant use standard phones
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But one without a model number apparently?
Let's see, it's been a long time but IIRC in an A series (A-308 etc) no you can't,
On the GX series I think you can plug a POT into any extension socket, but there might have been a proviso, something on the lines of BT configuring the trunks for pulse dial only otherwise the exchange heard each digit twice, once from the POTs phone itself and once from the system.
As I say, it was a long time ago.
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"The Natural Philosopher" wrote in message

DBS system by any chance ?
Andrew
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On Friday, 5 October 2018 09:48:44 UTC+1, The Natural Philosopher wrote:

Not normally. Historic phones do. Putting a cap inside a phone now costs less than dealing with customer returns.
NT
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On 05/10/2018 09:48, The Natural Philosopher wrote:

One way of doing this in a structured wiring environment is to use a RJ45 faceplate socket, and plug the digital phone straight in, and then use a Line Adaptor Unit with built in ring cap and traditional BT socket on it for the phones. The ones I use look like:
http://wiki.diyfaq.org.uk/index.php/Structured_wiring_system#Telephony

Many don't but some still do.
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Cheers,

John.
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On 05/10/2018 09:48, The Natural Philosopher wrote:

Very few. Remove the third wire, and wire it for digital. If you have the odd analog phone which doesn't have a built-in ring capacitor, connect it via an ADSL filter - whose PSTN outlet socket *does* have a ring capacitor.
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Cheers,
Roger
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On 05/10/18 20:44, Roger Mills wrote:

This sounds like a plan.
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