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)