SOTAP and SOADSL

I'm confused.

Mark J (a usually reliable source) here seems to imply that SOADSL is ADSL2+ broadband without the voice, and that SOTAP is/will be a transitional voice-only product for areas with neither FTTC nor FTTP. But this page is 4 years old, so maybe things have changed since. This more recent page describes SOTAP as SOGEA for ADSL, ie a data-only product.

SOTAP is unambiguously an OR product. It's described as broadband and voice over IP, so not voice-only. I can't find any mentions of SOADSL on OR webpages (but I might have missed some, of course). OTOH, BTW pages (eg the broadband checker) refer to SOADSL but not SOTAP. So is SOADSL just the BTW name for OR's SOTAP?

One commentator here seems to say that SOTAP is an umbrella term for SOADSL and SOGFAST (and possibly SOGEA too, it isn't clear (well, not to me)). Several others (example) say that SOTAP and SOADSL are the same thing.

And to muddy the water even more, last November something called 'SOTAP for analogue' appeared. This seems to be an emulation of the PSTN on the customer side, delivered to customer prem over copper, powered from the exchange, and carried over some network somehow. In this context, SOTAP seems to imply voice.

Please can anyone shed any light on all this, preferably with a few links/references to reliable sources?

Edited by Thaumaturge (Tue 27-Feb-24 12:20:50)

SOTAP is ADSL without WLR/PSTN. It is to ADSL what SOGEA is to FTTC.
It's a broadband only product but providers can add VOIP if they wish.
It is only available where ADSL is the only option.

SOTAP for analogue is a new product. It's a voice only product that doesn't need broadband to run over.
It is available nationwide but it is only available to existing users of landline only connections.
It saves them having to switch to a digital voice/VOIP product which in the case of FTTP would require 2 powered devices (ONT and Hub with phone port) and it will continue to work with care alarms/security alarms without them needing upgrading to work with VOIP.
Like SOTAP it is a temporary, transitional product.

I only found out about SOTAP for analogue this morning so excuse any inaccuracies in my post.

In reply to a post by j0hn83:

SOTAP for analogue is a new product. It's a voice only product that doesn't need broadband to run over.
It is available nationwide but it is only available to existing users of landline only connections.

Presumably that would require intact E-Side pairs and an exchange with functioning PSTN/WLR capability? If an exchange were to close due to the PSTN switch off then I guess the line would have to connect to another exchange?

Edit, just read this: Openreach states...that this solution “provides point to point copper access between an end customer premises and the CP equipment using pre-existing LLU [Local Loop Unbundling] ties within the exchange. It is required to allow end customers who have a WLR3 only line today, to maintain a working voice only service.” https://www.ispreview.co.uk/index.php/2023/11/openre...

Edited by 4M2 (Tue 27-Feb-24 16:37:47)

In reply to a post by 4M2:

In reply to a post by j0hn83:

SOTAP for analogue is a new product. It's a voice only product that doesn't need broadband to run over.
It is available nationwide but it is only available to existing users of landline only connections.

Presumably that would require intact E-Side pairs and an exchange with functioning PSTN/WLR capability? If an exchange were to close due to the PSTN switch off then I guess the line would have to connect to another exchange?

It will need an exchange with E-Side yes.
I think there's only 5 exchanges planned to close with PSTN. There's a total of only 100 due to close by 2030 which is when this product is intended to last until.

It should only require a PSTN card in the ADSL MSAN, which is already how Talktalk do their landlines.
It won't use any of the PSTN kit, that is still being retired.

https://www.ispreview.co.uk/index.php/2023/11/openre...

Seems like we both found that ispreview article today

It great news that analogue voice lines can be retained - the idea of VOIP as a possible total placement for PSTN after 2025 did seem somewhat unreasonable.

Thanks folks, but what then is SOADSL, and how does that fit into the picture?
That was really the point of my OP.

In reply to a post by Thaumaturge:

Thanks folks, but what then is SOADSL, and how does that fit into the picture?
That was really the point of my OP.

Exact same thing.

Openreach have a product called SOTAP.
BT Wholesale buy SOTAP and sell it as SOADSL.
Different terminology for the same thing.

That's what I guessed in my OP, but I couldn't find confirmation anywhere. Thanks for clarifying.

What distance does SOTAP / SOADSL work over?. We have a friend who lives on the edge of Bodmin Moor over 10km from the Green Box and a further mile + from the exchange. BT switched her over to a digital system last year, which didn't work and left her without a phone for 5 weeks. So she is very hesitant in signing a contract for a switch to SOTAP / SOADSL. Its impossible to contact Openreach to speak to a techie who can answer my query.

Over 10k and a mile more to the exchange ? ADSL *might* just sync, but I wouldn’t rely on it.
Different technology and a VOIP service via that might be a better idea. No mobile signal I suppose ?

The same as ADSL2+ so problematic beyond 6km, especially if the cabling is not in good condition. Did they have just a plain phone service or broadband also before the switch last year?

Can you please clarify, does your friend need just a telephone service or is broadband a requirement too?

Just a telephone service. Thanks

Just a plain telephone. The 3 engineers from Openreach who attended the problem last year said a digital service would never work. Have raised this issue with OFCOM why do BT sell a service that would never work. Left hand not talking to the right hand I guess. With no mobile service it was hell for her for 5 weeks. She is now very hesitant to sign up for what BT are proposing now.

In reply to a post by desken:

Just a telephone service. Thanks

In my opinion the only solution is 'SOTAP for Analogue' (aka PDPL) until full fibre is available. This is where a digital voice service goes through a digital to analogue converter (in the exchange) and is presented to the customer like a legacy telephone service (aka PSTN). Once full fibre is available a full digital voice service can then be provided.

Edited by PCJM40 (Mon 12-Oct-26 16:36:52)

So how did BT resolve the issue of 5 weeks without service, did they revert to the former PSTN setup?

You would have expected BT to have checked that service was possible beforehand, the wholesale checker https://www.broadbandchecker.btwholesale.com/ will show what is available.

Given the distance involved and the anecdotal comments from the Openreach engineers it would suggest that they should have offered migration to the BT Wholesale Pre-Digital Phone Line (PDPL) / Openreach SOTAP for Analogue* product which keeps the existing arrangement at the customer premises with the conversion to digital being handled at the exchange.

* this is not the same as the Openreach SOTAP product.

PDPL as said really is the only possible copper-based voice solution that could be (technically) viable here.

Saying that I do wonder what maximum line lengths Openreach have actually tested it to ( know its a temporary drop-in replacement for PSTN voice, but its not exactly the same). Bodmin would be one of the more extreme edge cases.

Ultimately if/when copper completely disappears, then for a terrestrial connection fibre is the way - but this would be one heck of a build cost for presumably a handful of properties. Maybe it would be easier / cheaper to actually keep PDPL in perpetuity....

You would have expected BT to have checked that service was possible beforehand,

Trouble is, often this is sales people pushing the products …

Back in the day, when ADSL had just gone rate adaptive. We would repeatedly go out to the same properties in the boonies near Twyford, Berks. The three local cabs were 12, 13 and 14k from the exchange. You could swap out the E side onto the lowest attenuation one, but still no sync.

You’d tell the punters, but they wouldn’t accept it, because whoever sold it to them insisted it would work .
Some would sell their properties due to this, and 6 months later, you’d be back doing the same thing.

Thanks.
One afternoon when we were at our friends property she was passed to 4 or 5 BT persons - before we were passed to someone who understood and eventually resolved the problem. By going back to the original PSTN set up, but with a different phone number. It took another 3 or 4 days to revert to the original phone number.

Have looked at the test results from the test link -

SOADSL Products Downstream Line Rate (Mbps) Upstream Line Rate (Mbps) Downstream Range(Mbps) WBC SOADSL Availability Left in Jumper
WBC SOADSL 2+ Up to 1.0 -- 1.0 to 3.5 Available --
SOADSL Max Up to 1.0 -- 0.75 to 2.5 Available --
SOADSL Fixed Rate Up to 0.5 -- --

Alarmingly when I raised the issue with OFCOM, after the initial 8 weeks of the problem arising, BT’s response to OFCOM was there’s not an issue !
I rejected this as an answer and BT then accepted there was a problem.

Speaking with a manager from BT Plymouth he tells me that the procedure between BT and Openreach has been improved ! I understand it use to work like this BT raise a contract with Openreach. Openreach then go and do the work as directed. But now the order to Open reach is different and if the Openreach engineer has issues or foresees issues the engineer speaks with BT! Remember BT had a slogan “ It’s good to talk”. !

Those figures suggest a line length around 6km, and if true SOADSL + Digital Voice would work. However records can be wrong and trying to get to anyone who can fix them is often difficult - if the line is 10km+ then PDPL is going to be the only reliable solution, it just* a case of getting BT to accept that.

* unfortunately easier said than done

In reply to a post by Pheasant:

Maybe it would be easier / cheaper to actually keep PDPL in perpetuity....

People move house. When they cease their PDPL line the next occupier won't be able to take it - it's not available for new provides or working line takeovers (*). Naturally over time the number of lines will tend towards zero.

After a decade or so, the last few holdouts will likely be offered something else. During that time, the Shared Rural Network should have reduced the number of mobile not-spots, so it will likely be a terrestrial mobile service for most, and satellite for anyone else.

For the OP: do nothing. Stay on the analogue PSTN service you are on, keep paying for it, and you should be moved to the continuation service transparently when PSTN is switched off.

(*) Possibly if people raise loud enough complaints under the USO, and/or get their MP involved, there might be some exceptions granted.

It was a slightly tongue in cheek comment, but they will have a job to decide how to viably continue service to some of the technically more challenging edge cases like this once PSTN goes and they retire PDPL in March 2031