Testing a Phone Line

Not sure if this is the right place to post but here goes.

I just wondered if the line test service (accessed by dialling 17070) is a facility which is standard on ALL providers PSTN lines or if it can/should differ based on your provider? IE, assuming it's an Openreach product, do they offer different "versions" or is down to the type of line you have?

I am with TalkTalk and when I dialled 17070 (to use the quiet line test) it's not available on my line. I just get my number read back to me.

I this specific to TT?

The standard 17070 service is on lines connected to an Openreach telephone exchange.

If you are on a Talktalk line then this uses LLU (local loop unbundling), which means your copper pair doesn't touch the Openreach exchange at all: it goes directly to a piece of Talktalk equipment called an MSAN - basically a DSLAM with voice. It's housed in a separate rack in the same exchange building.

Whatever test numbers and services Talktalk decide to provide is entirely down to TT themselves and how they configure their MSANs and voice network. So if Talktalk have decided to provide a 17070 service, but it works differently to Openreach's, that's entirely to be expected.

Whilst I agree with your reply, the OP a has

Currently on TalkTalk Fibre 150

in their signature …. so even less likely for 17070 to work


[edit]Hang on, that might be a g.Fast service

Edited by Zarjaz (Sat 10-Dec-22 12:47:25)

Surely the copper does hit Openreach kit on entry to the exchange? (I forget what it's called). Linked from there to either a BTW MSAN or an LLU supplier's one.

The 17070 response is though from the linked MSAN.

In reply to a post by pluralist:

Surely the copper does hit Openreach kit on entry to the exchange?

A passive connection panel?

In reply to a post by pluralist:

Surely the copper does hit Openreach kit on entry to the exchange? (I forget what it's called). Linked from there to either a BTW MSAN or an LLU supplier's one.

The 17070 response is though from the linked MSAN.

The frame (MDF)

Exactly. It hits a patching frame, which links the copper. In the case of LLU lines this is patched onwards to the third-party provider's equipment; it does not touch the actual telephone "exchange", i.e. the Openreach equipment which provides analogue telephony service, dialtone etc.

I believe some exchanges have automated patching frames, which can move the jumpering remotely. Otherwise, an engineer has to visit the exchange to re-jumper a line.

Any clues as to how long TT intend to maintain their MSANs after end of 2025?

I’ve heard that they won’t retire their analogue voice for a while yet - at least they don’t intend to sunset it imminently like Openreach.

Never come across an ‘automated patching exchange’. Some lines will reuse previous PSTN equipment already allocated to particular bar pair/ line. But this scenario doesn’t include any LLU equipment.

Lines from LLU kit will be jumpered via an allocated TAMS port allowing for remote testing by Openreach staff.

17070 doesn't work on LLU lines but you can reach the exact same testing facility by dialling 02087599036

Edit: I don't have a PSTN line to test the number but dialling from my mobile doesn't offer a quiet line test. It definitely worked on my old Talktalk FTTC line (though a fair few years ago now).

Edited by j0hn83 (Sun 11-Dec-22 20:05:03)

In reply to a post by Pheasant:

Any clues as to how long TT intend to maintain their MSANs after end of 2025?

I’ve heard that they won’t retire their analogue voice for a while yet - at least they don’t intend to sunset it imminently like Openreach.

TalkTalk I believe use Openreach 's LLU SMPF and SLU SMPF product which is included as being impacted by Openreach WLR/PSTN closure, https://www.openreach.co.uk/cpportal/products/the-al... therefore I would have thought TalkTalk would need to follow the same times as published by Openreach for the All IP Programme.

I know TalkTalk VoIP (TalkTalk Digital Voice) is available in the Openreach All IP Testing Lab and they have been working with and testing products such as telecare/care line products on their Digital Voice service. I would expect by September 2023 mass migrations would start to begin.

In reply to a post by Zarjaz:

Whilst I agree with your reply, the OP a has

Currently on TalkTalk Fibre 150

in their signature …. so even less likely for 17070 to work


[edit]Hang on, that might be a g.Fast service

Yes this is a g.Fast service. Apologies if I didn't include that (may edit SIG)

In reply to a post by j0hn83:

17070 doesn't work on LLU lines but you can reach the exact same testing facility by dialling 02087599036

Edit: I don't have a PSTN line to test the number but dialling from my mobile doesn't offer a quiet line test. It definitely worked on my old Talktalk FTTC line (though a fair few years ago now).

Oh OK I will try that, the reason for the test is that I get random dropouts of my connection and I wanted to check if it was a voice issue. I also briefly purchased a corded phone (which I returned to Argos) to try and test if there was any noise on the line before reporting it as a Broadband issue to TT.

17070 is something of a legacy, from when an ‘exchange line’ was pretty much a jumper wire between the exchange equipment, (System X line concentrator, or System Y LIC ) ,and the MDF cable bar/pair , there is built in functionality for the exchange to test any PSTN line , via the LIC or H/W Conc , accessed by a ‘proper’ line test system access available to those ‘control’ staff that require it , it was simple enough to make a basic test facility available to field technicians /engineers to do a test themselves by dialing 17070 , several other ‘tests’ were also available , (rather than the tech having to ring ‘control’ and ask for the line to be tested ) , obviously this number in time became known by the general public.
MPF LLU providers ( Sky and TT being the biggest in this area ) don’t use the BT exchange LIC or H/W Conc , as Sky or TT telephony is completely within their own networks so this OR line test service is inaccessible by them.
If TT or Sky wanted to provide something similar from within their networks, they could do so , although the testing path would be nothing like the ‘BT’ one.
When providers like Sky and TT used SMPF , ( shared metallic path facility) the telephony was supplied by the BT exchange so 17070 would work in the same way as BT customer , but SMPF is now extremely rare

Edited by Iniltous (Mon 12-Dec-22 18:02:14)

Several years ago I had BT based broadband and a WLR line which developed a fault: when the phone rang the broadband connection would be lost. In order to fix the problem an Openreach SFI engineer attempted to solve the issue without any success. Due to extended delays in getting the repair done I migrated the broadband to a TalkTalk Business based connection which resulted in a SMPF service from my provider for voice (WLR) and broadband (TTB). This solved the fault and I have happily been with SMPF ever since.

The reason for this success has never been fully explained to me, perhaps you may have some thoughts on this subject?

Edited by 4M2 (Mon 12-Dec-22 20:16:06)

Before the 17070 system, in the 80s and 90s in my district we could dial into the Teradyne 4Tel system that also offered to perform interactive tests too. Ask it to and it would put a test tone on and when you looped it it would perform measurements and advise distance to fault from where you had your loop on. Great system.

Think the 17070 system was deliberately dumbed down as it was also Teradyne in my area and didn't even give voltage measurements. But the ability to disconnect and loop the exchange remotely was something I would have given my best twisting cutters for.

Edited by FibreBubble (Mon 12-Dec-22 20:52:47)

Automatic MDFs were always a pipe dream in the UK. The nearest we got in my district was 'exchange stabilisation' in which the idea was connecting all MDF pairs through to the exchange and so could be switched by the nice fellows on the OMC.

Spares on the MDF were routed to DPs so even more of a glorious automated switching future was predicted.

Other ideas in my district were tried such as Cosmic Frames to minimise jumper lengths and eliminate ladders to increase production.

Of course ADSl and LLU overlays ended it all.

Edited by FibreBubble (Mon 12-Dec-22 20:59:39)

In reply to a post by cymru123:

TalkTalk I believe use Openreach 's LLU SMPF and SLU SMPF product which is included as being impacted by Openreach WLR/PSTN closure

No, they don't. They use MPF, not SMPF.

SMPF is the *shared* metallic path facility, where the broadband signal goes to the ISP's data-only DSLAM and the narrowband signal goes to the Openreach exchange. There's a splitter, similar to your home broadband splitter.

MPF is a dedicated metallic path all the way to the ISP's MSAN, which handles both voice and data.

In reply to a post by j0hn83:

17070 doesn't work on LLU lines but you can reach the exact same testing facility by dialling 02087599036

Edit: I don't have a PSTN line to test the number but dialling from my mobile doesn't offer a quiet line test. It definitely worked on my old Talktalk FTTC line (though a fair few years ago now).

j0hn83 just wanted to let you know that number worked! I got the FULL OR line test facility.