Switch off of PSTN + bandwidth question

Hello

Now that BT will eventually retire PSTN and a move on to Digital Voice, will we get more bandwidth on the main internet line (higher sync speed?) to compensate over the PSTN section (that will be turned off)?

TIA

Whilst they use the voice frequencies for vdsl, and that would give some extra bandwidth a) other wholesale operators such as talk talk will continue offer analogue phones.

the point here is that, by the time everyone is off analogue phone, 90% plus will have gigabit capable connections rendering your idea pointless.

The hassle of reconfiguring the DSLAM'S, Openreach changing their bandplan, updating documents, tweaking the MCT tests, for what? It's worth somewhere around 160kbps.

POTS only uses a single tone for voice with another 4 tones used as a guard band to prevent crosstalk between voice and the start of the 1st upstream tones (u0).

As mentioned LLU operators will be able to continue using that frequency for voice so what you suggest isn't possible, but it wouldn't be worth it anyway.

Highly unlikely. Would require permission from Ofcom and while Openreach are withdrawing PSTN doesn't mean Sky, TalkTalk and Vodafone will immediately and Openreach will need to give them notice after approval from Ofcom.

Not really worth it for that tiny sliver of spectrum.

I'm on BT FTTC+Digital Voice last 1 year and 5 months.

My analogue line is basically turned off. I have not observed much increase in bandwidth compared to that of TalkTalk.

Data rate:18.965 Mbps / 78.572 Mbps
Maximum data rate:18.965 Mbps / 81.309 Mbps
Full Fibre (FTTP) Mode:Off
Noise margin:6.2 / 3.5
Line attenuation:10.6 / 16.7
Signal attenuation:10.6 / 18.2

So, these are my stats. Even though my BT Smart Hub 2 is reporting a maximum data rate of 81.3Mbps my router doesn't seem to hit anything higher than 78 or 79Mbps since migrating to them from TalkTalk.

I think crosstalk is a far bigger factor to speed than simply switching from analogue to digital voice.

I would get 80/20 for the first 9 months with TalkTalk in 2020 with an SNR of 6dB but gradually over the next 15 months the SNR dropped to 3dB and achieved same sync speed of 80Mbps before slowly dropping between 76-79Mbps and this is where it has been hovering for nearly 2 years.

However, migrating to BT with DV did not make much difference in attaining higher speeds any more.

For example, despite having DV my sync speeds aren't much different with BT compared to TalkTalk over the last 2 years.
Perhaps, indeed like J0hn83 mentions this speed can only account to around 160Kbps increase.

You'll hardly see any difference in router stat comparisons. The only positive difference I see with DV as mentioned before, I no longer experience connection drop-outs when picking up the phone or when the phone rings!
I know I've mentioned this before and was told I simply masked the problem rather than solve it. However, this is still a positive change as it will not trigger DLM.

Connecting traditional phone into the master socket doesn't receive dial tone so that stops this technical problem of connection sync being lost. This in turn might increase the speed ever so slightly. The biggest positive observation is reliability in connectivity with DV! If anyone has experienced connection drop-outs similarly to the days of dial-up when picking up the phone then rest assured that DV will resolve this particular problem & perhaps DLM will not trigger lower connection speed re-syncs.

Short answer: no. Voice frequencies (up to 4kHz) are not used for data, apart from dial-up modems

Longer answer: FTTC and ADSL do use non-overlapping frequency bands. There are FTTC profiles available which cover both bands, which would make FTTC work both faster and over longer distances, but can't be used until all ADSL is gone.

Turning off ADSL isn't going to happen, because there are LLU operators like Talktalk and Sky who have their own DSLAMs in the exchange, and are providing DSL services.

By the time all of those have gone, then pretty much the whole country will be on FTTP anyway. At that point we won't be talking about optimising FTTC: we'll be talking about removing the FTTC cabinets entirely.

Post deleted by witchunt

In reply to a post by BLaZiNgSPEED:

My analogue line is basically turned off. I have not observed much increase in bandwidth compared to that of TalkTalk.

The ISP chosen usually makes zero difference to the sync speed. They all use Openreach's FTTC/VDSL2 DSLAM's with the same profile (17a) and with the same bandplan.

There can only be a difference in sync speed if the providers use different DLM policies. Openreach have 3 DLM policies to choose from, Speed, Standard & Stable, though almost every provider uses Speed or Standard. I've only ever seen business ISP's use Stable.

The difference in the Speed & Standard policy might be the difference between a line using a lower SNRM target or not. It usually makes no difference though. Any immediate difference in sync speed when changing provider is simply because the DLM is often reset upon migrating.

Having an active PSTN/POTS line vs having VOIP/Digital Voice will make zero difference to your sync speed though. The voice tone is never used for data and there's a guard band in place that means the voice tone doesn't cause any interference/crosstalk.