Telephone Ringback Code?

Good afternoon, again, David,

Thank you for your interest and for your posts.

Regarding the 'master' socket in our original Virgin landline installation:

It isn't a 'master line-box'. It looks like any other surface mounting single 631A or 431A phone socket.

I've always accepted the regulation that subscribers/customers are not permitted to tamper with the phone supplier's wiring.

I would certainly never tamper in the extreme way that regulation was intended to prevent - if, for example, mains voltage gets on to the phone network, there may be no local evidence of a problem yet some poor BT/Open Reach/Virgin linesman sat on the edge of a cable pit may be the one who suffers the consequences.

My practice, in three residences in turn now, has been to install a socket adjacent to the company's 'master' socket and to wire my extension tree from there. Most of 'my' wiring is 6-core phone cable, some buried in the wall plaster and some routed beneath the upstairs floor-boards. Its configuration is part 'daisy-chain' and some branches. I've installed a 631A plug on a short flexible pigtail out of the side of my basic box and connect to the company's system by plugging that pigtail into their master box. This configuration permits simple and complete disconnection of my wiring from theirs in the event that troubleshooting is required. I believe that Nick has the same set-up. Maybe I should take and post a photo.

In the current situation, the old landline master socket (and my base box) are at the opposite end of the living room from the position of the hub (router). Neither is at all simple to move. So when appropriate, I have bridged from the Virgin adaptor to my pigtail using a six metre 4-core flexible extension cable. (And, at different times, a 6-core flexible extension cable, no difference in system behaviour.)

We have four phones, two labelled REN=1, the other two unlabelled. I beleive that the unlabelled phones are also nominally REN=1 each. My hunch is that our hub is a bit deficient in the ring department and the actual ring load is pulling down the delivered ring drive signal to the point where only a single phone that happens to have a very low real REN will ring. The phone that does actually ring isn't doing so as stridently as it did before the chengeover.

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 27/06/2022 14:15:25

Frances,

Thank you for your post. I'll ponder thereon.

Best regards,

Swarf, Mostly!

It sounds as if the line is not delivering enough voltage (70-90v RMS AC) to cause the phones to ring. The Decor phone may be more sensitive and operate at at a lower voltage than the other 3.

I don't know where the ring voltage is generated by Virgin. On BT lines it originates at the exchange. I have a VOIP adapter (ATA) in which the ring voltage, frequency and cadence can be adjusted. If I set the ring voltage too low, the phones won't ring.

I suspect your Virgin hub into which you plug the adapter is either faulty, or needs the programming adjusting.

If you can. hook a multimeter across the phone lines, in parallel with a phone, and call your own number - or use a ringback test - to see if you can measure the ring voltage

I was also thinking the problem may be due to the lack of the capacitor that is fitted in the master socket between connections 2 & 3. .Older phones rely on the ring signal being being coupled to terminal 3. Modern phones only seem to need connections 2 and 5 to work. Provided your existing wiring includes a link between connection 3 of all the sockets only one master socket is required. So either add a 1.8 uF capacitor between connections 2 and 3 of one of the sockets OR replace any one of the sockets with a master socket. Regarding REN numbers. I think many modern phones put much less a load on the ringing circuit than a REN number of 1.
I have recently change to BT FTTP and the phone port on the Smart hub 2 works with two of our existing phones and a DECT base. (Non of our phones required the bell wire connection to pin 3 of the socket.)

Les.

Edited By Les Jones 1 on 27/06/2022 14:38:20

Edited By Les Jones 1 on 27/06/2022 14:38:56

Here are some notes I made for the changeover to FTTP

Here is the information on the two ring signals.

For phone service from exchange via copper wires.

Ring sequence.
Voltages with respect to A line. (Plug pin 5)

Static state of B line -50 volts (Plug pin 2)

Incoming call line goes to about +50 volts with ring tone superimposed on it

Ring frequency about 25 hz (About 53 volts rms.)

T = 0 DC level goes from - 50 to +50 volts
T = 1.60 seconds Start of first ring tone burst.
T = 2.0 seconds end of first ring tone burst
T = 2.2 seconds start of second ring tone burst.
T = 2.66 seconds end of second ring tone burst.
T = 4.7 seconds Start of next pair of bursts.

Gap between pairs of bursts about 2.1 seconds.

For phone port on BT Smart Hub 2.

Ring frequency about 25 hz (About 54 volts rms.)

T = 0 DC level goes from +48 to -48 volts
T = 1.50 seconds Start of first ring tone burst.
T = 1.9 seconds end of first ring tone burst
T = 2.1 seconds start of second ring tone burst.
T = 2.5 seconds end of second ring tone burst.
T = 4.5 seconds Start of next pair of bursts.

Gap between pairs of bursts about 2.0 seconds.

Les.

I now have the phone port on the Smart Hub 2 working with two phones and a DECT phone base.

I think that's right: distinctly possible that ordinary domestic acoustic to digital adaptors aren't made to cope with customers who have installed elaborate daisy chains of handsets in multiple rooms,! They might assume a maximum of two or three, partly because the fuss-free installation of DECT wireless phones makes unlikely the average customer will want to install wires. DECT supports as many handsets as you like and only the base station counts as a load, which is 1 REN or less.

I think you need to look at big house or commercial building technology, sort of place that has several extensions, but doesn't need a PABX. Quick look on Amazon found only one suitable 10 REN device, but I expect BT and other providers do them as well

.

Overloading the adaptor is the most likely cause, but I think there's more than one type of REN. Some older phones respond to a ring signal by swinging a resonant mechanical clapper, whereas newer types usually just sound a buzzer. The former type is much fussier about the ring signal it gets, both in terms of frequency and the amount of oomph needed to ring the bell.

30 years ago ancient phones were a big problem in terms of REN, and the Post Office were red-hot careful about not letting customers overload their delicate exchanges! Remember Blue Spotting? The REN problem faded because electronic phones don't need lots of energy to sound off, but it can still bite. My ex-GPO technician friend knew all about this stuff but he moved away. Any ex-GPO types on the forum who can advise?

Dave

Random thought about ring capacitors. Some of the old ADSL filters (the ones fitted between phones and the line) contained their own ring capacitor. Newer ones (as far as I know) don't - on the assumption that modern phones only use two wires.

If you have an old ADSL filter in the junk box, try putting it between one of the phones that don't work and the Virgin adapter.

Only necessary to spend more money: 'the Snom M900 multicell DECT base station supports up to 4,000 base stations and up to 16,000 DECT handsets'

Finding high-end equipment can be difficult for domestic customers who are assumed to be technically illiterate. We're usually only sold off-the-shelf gear that's kept basic so the seller doesn't get incoherent support calls from innocents completely out of their depth! Businesses are better placed, having lots of options such as in-house specialists, consultancy budgets, and contracting.

Perhaps the easiest solution is to buy another base station and run it in parallel. The main disadvantage is the handsets couldn't intercom between base-stations.

Dave