BT-supplied ATA191 (or ATA192) - default ring voltage

[jgwi...@gmail.com]

Does anyone know what ring voltage BT configures its ATA191/ATA 192 Analogue Voice Adapters to use?

I have just helped set up Cloud Voice Express for our village pub. The pub has a non-BT router without a VOIP port (and it makes sense to stick with that). BT had provided a Cisco ATA191, and I had followed the included BT instructions to try and connect and configure it. I had failed: it eventually turned out that despite the BT instruction leaflet, I ATA191 or ATA192 configuration needs an engineer visit.

The engineer came yesterday to configure the ATA191. The configuration took nearly two hours and I was short of time so couldn't test everything before the engineer left, but the ATA191 was handling inbound and outbound calls to a reasonably modern corded handset, so all looked good.

But testing everything later, there is a problem. I think the ring voltage is too low.

An old BT-branded phone handset fails to ring when connected to the ATA191 but rings on my domestic PSTN landline.

Incoming calls aren't being seen by the ancient SouthWestBell 1+8 PBX (REN=4) that the publican wants to continue using.

I found an old BT REN booster and tested it on my domestic PSTN landline - it works, and you can hear the relay click with each ring. I connected it to the ATA191 extension socket, and it didn't click (and the PBX still didn't ring).

So I am suspecting that the ATA191 is set with too low a default ring voltage for older equipment. Does anyone know what the default setting is? And what are my chances of getting BT to set it higher?

[notya...@gmail.com]

On Wednesday 14 February 2024 at 07:55:41 UTC, jgwi...@gmail.com wrote:
> Does anyone know what ring voltage BT configures its ATA191/ATA 192 Analogue Voice Adapters to use?
>
> I have just helped set up Cloud Voice Express for our village pub. The pub has a non-BT router without a VOIP port (and it makes sense to stick with that). BT had provided a Cisco ATA191, and I had followed the included BT instructions to try and connect and configure it. I had failed: it eventually turned out that despite the BT instruction leaflet, I ATA191 or ATA192 configuration needs an engineer visit.
>
> The engineer came yesterday to configure the ATA191. The configuration took nearly two hours and I was short of time so couldn't test everything before the engineer left, but the ATA191 was handling inbound and outbound calls to a reasonably modern corded handset, so all looked good.
>
> But testing everything later, there is a problem. I think the ring voltage is too low.
>
> An old BT-branded phone handset fails to ring when connected to the ATA191 but rings on my domestic PSTN landline.
>
> Incoming calls aren't being seen by the ancient SouthWestBell 1+8 PBX (REN=4) that the publican wants to continue using.
>
> I found an old BT REN booster and tested it on my domestic PSTN landline - it works, and you can hear the relay click with each ring. I connected it to the ATA191 extension socket, and it didn't click (and the PBX still didn't ring).
>

Later phones and faxes don't ring by voltage, but signal.

[jgwi...@gmail.com]

> Later phones and faxes don't ring by voltage, but signal.

Can you help me understand this a bit?

I understand that modern devices don't have an electromechanical bell needing powering, but I thought that, if only for simple handsets, there had to be some volts pulsating to indicate ringing - even if at only a very low current? If not a voltage, what form does the signal take, please?

[notya...@gmail.com]

Back in the old days phones had just two wires A and B. The normally carried 48V DC and ~90V AC when ringing.

To have two phones you had to uncouple a connection inside the handset and link them together, so that for dialing the phones were in parallel and for ringing in series. I learnt how to do this by examining ones that had already been installed by the GPO.

When BT went over to plug and sockets from 1981, the A and B wires were presented on pins 2 and 5 and the ring extracted in the master socket (which contained passive components) and presented on pin 3 of the master and slaves (no components), but not necessarily 90V AV. Phones had a designated REN (Ring Equivalence Number) and you could have up to 4 handsets. Some modems etc. had an REN of 0.

Try a different handset.