BT DV and answering machines

Mercifully I'm not with BT, and haven't been for yonks. But some folks in my village who are have been receiving letters from BT, dated no more precisely than Sept 23, saying that they are going to be moved over to digital voice "within the next 30 days".

1) Within the next 30 days might be tomorrow. That doesn't seem very much notice for someone who might be away on business or holiday or ill when the letter lands, and who might need to arrange to have things like security or telecare systems upgraded. Does anyone with experience of this process know how flexible or helpful BT are about allowing time to get this kind of thing sorted?

2) The leaflet enclosed with the letter states "you won't be able to use a standalone answer machine [with DV]". I'm puzzled by this. How do BT detect whether a human or a machine has picked up the phone, why should they need to, and why should they care anyway? I've had VoIP (with Voipfone) for a couple of years now. I have a DECT phone with integral answering machine in the base station, it's not an IP phone (it just has a 431A plug) but I'm happy with it and have no wish to update it, it's connected to my router via an ATA box, and it works just fine with Voipfone. So why is BT DV apparently so fussy?

3) Is it perhaps something to do with the "standalone", ie a separate box currently wired to an extension? I can see that in such a case it might be necessary to do a bit of rewiring so that all the extensions are connected to the router, but shouldn't it still be possible to get it to work? Has anyone done it?

As far as 2 is concerned I had a DECT base station with built in answerphone and 2 handsets and it worked fine with DV (no longer have voice at all as changed ISP). Can't see why an answerphone wouldn't work so long as it is compatible with standard voice.

One of the main issues with answering machines (and other devices which have historically plugged into the incoming phone line such as call screening, telehealth and alarm signalling) is that they may not be able to reliably detect an end-of-call and hang up their connection.

The most reliable method is the 'K-break', not all VoIP interfaces provide this (see https://forums.thinkbroadband.com/zen/t/4740852-re-d... as an example), otherwise devices should detect a Number Unobtainable tone. However some VoIP interfaces instead generate busy/reorder tone, especially if they have not been configured to simulate the BT network tones.

So they may work, or may not. Anything which does tone signalling not using standard DTMF, e.g. BSIA Fast Format Protocol, may also have issues.

There has been plenty of coverage regarding the BT DV migration, e.g. https://www.ispreview.co.uk/index.php/2023/08/bt-rol... and the previous articles linked therein, which should exclude customers who are over 70 / only use landlines / no mobile signal / who have disclosed any additional needs but supposedly only if BT are aware of those circumstances.

In reply to a post by tdw42:

One of the main issues with answering machines (and other devices which have historically plugged into the incoming phone line such as call screening, telehealth and alarm signalling) is that they may not be able to reliably detect an end-of-call and hang up their connection.

The most reliable method is the 'K-break', not all VoIP interfaces provide this (see https://forums.thinkbroadband.com/zen/t/4740852-re-d... as an example), otherwise devices should detect a Number Unobtainable tone. However some VoIP interfaces instead generate busy/reorder tone, especially if they have not been configured to simulate the BT network tones.

So they may work, or may not...

OK, that's interesting. But we're talking specifically BT DV and BT HH2 here. So do BT appear to be saying that a box which currently connects OK to the PSTN, and so presumably can detect end-of-call signals correctly on that, may not work OK with the VoIP interface in the HH2? In other words, BT's HH2 VoIP interface may not be doing a proper emulation of BT's PSTN signalling?

And why should a "standalone answer machine", whatever that is, be different from one integrated into, say, a DECT basestation, some of which are known to work?

In reply to a post by tdw42:

There has been plenty of coverage regarding the BT DV migration, e.g. https://www.ispreview.co.uk/index.php/2023/08/bt-rol... and the previous articles linked therein, which should exclude customers who are over 70 / only use landlines / no mobile signal / who have disclosed any additional needs but supposedly only if BT are aware of those circumstances.

I saw the ispreview article. It was a bit unclear how much was specific to NI, and how much applied more generally to the UK (I'm not in NI). The person who showed me her/his letter doesn't fit into any of the exclusion categories, and should be able to cope. But we have do quite a number of older folks around who are on BT and might be rather confused by it all. It's sidetracking a bit, but there was also a recent article linked here about an older people's pressure group withdrawing support for BT's DV rollout on account of them allegedly forcing some over-70s who have not opted in onto DV.

It all seems rather a mess to me.

For what it's worth the answering machine built into my DECT base works fine with an ATA (Cisco ATA191) and detects the end of the call without issue. I can only guess that BT are being overly cautious in saying that answering machines won't work, and possibly it's because they provide 1571 with DV.

Essential voicemail is free with DV , there doesn’t seem to be anything conclusively stating if it can be switched off or not by the consumer, if it cannot be switched off , then having another competing answering device isn’t a good idea ,
BT by advising that a stand-alone answer machine should not to be used hopefully saves consumers calling BT to report a fault , saying they know a message was left for them , but there is nothing on their own answer machine , and why does BTDV dialtone sound like busy tone , when it’s actually the modulated dialtone signifying a message left on voicemail 1571, there was a post on the BT Community forum with pretty much this situation.

Edited by Iniltous (Mon 11-Sep-23 16:47:03)

In reply to a post by Thaumaturge:

In other words, BT's HH2 VoIP interface may not be doing a proper emulation of BT's PSTN signalling?

Yes

And why should a "standalone answer machine", whatever that is, be different from one integrated into, say, a DECT basestation, some of which are known to work?

The known working device may look for any of the end-of-call signals, or the HH2 may be producing the correct signalling.

I saw the ispreview article. It was a bit unclear how much was specific to NI, and how much applied more generally to the UK (I'm not in NI).

As the article mentions NI is the latest area, following Yorkshire & Humber and East midlands, with North West and London coming up.

In reply to a post by jpm:

For what it's worth the answering machine built into my DECT base works fine with an ATA (Cisco ATA191) and detects the end of the call without issue. I can only guess that BT are being overly cautious in saying that answering machines won't work, and possibly it's because they provide 1571 with DV.

So does mine, as I said in my OP, but that's with Voipfone and a Grandstream HT801. Is yours with DV?

In reply to a post by Iniltous:

Essential voicemail is free with DV , there doesn’t seem to be anything conclusively stating if it can be switched off or not by the consumer, if it cannot be switched off , then having another competing answering device isn’t a good idea ,

In fairness the leaflet does suggest people use the free 1571 as an alternative. It's possibly true that having 2 answering services is a bad idea, but it's what I do. Our local answering machine cuts in first, and if we're at home we can monitor it as a simple form of call screening. If for whatever reason the local machine doesn't pick up, then Voipfone's voicemail will intercept on a somewhat longer timeout. This was useful just a couple of weeks ago when our internet was down for a day due to a faulty ONT. But Voipfone's voicemail is very configurable as to timeouts etc, which makes this possible; if BT's isn't, and can't be turned off, then obviously there might be conflict issues.

BT by advising that a stand-alone answer machine should not to be used hopefully saves consumers calling BT to report a fault , saying they know a message was left for them , but there is nothing on their own answer machine , and why does BTDV dialtone sound like busy tone , when it’s actually the modulated dialtone signifying a message left on voicemail 1571, there was a post on the BT Community forum with pretty much this situation.

I suspect there's some truth in this, they are trying to reduce the support load caused by all manner of 3rd party boxes on their lines.

BTW, I think I should have referred to the Smarthub 2 (SH2) previously, not the Homehub 2 (HH2). Apologies - I'm not very familiar with all these BT boxes.