Power cut communications

[goslow]

My area experienced quite a big power cut yesterday evening (large area affected and 2 or 3 hour duration). While waiting for the power to come back on, I thought I would try a bit of 'research' to see what devices/systems still functioned with the power off. The results weren't too encouraging.

No mobile to mobile voice connections were available (on the EE network), no data available, text messaging working slowly but not reliably. Mobile signal levels showing on the phone dropped (presumably connecting to more distant masts still with power or a backup supply). Suppose this whole mobile network behaviour could be by design (to prioritise emergency comm's when the power was off or maybe some local aspects of the mobile network simply stopped working when the power went off)

Landline phone (from VM, currently via conventional wall socket) did still have dial tone with a corded phone plugged in. Didn't try actually ringing anyone since mobile numbers did not appear to work and receiving landlines would probably be cordless or increasingly fed from routers, so wouldn't work anyway.

Left me thinking that the powers that be have now painted us into a bit of a communication-corner here, esp. with the phone conversion to 21CV phone lines, because the evidence from yesterday seemed to be that when the power went off, pretty much everything stopped working apart from (intermittent) text messaging.

[Andrew-G]

Vulnerable customers can request battery back up units, and in some cases customers can rent them (don't know if VM will), but that only tends to protect against quite local outages and quite short ones.  In the case of protracted and widespread power loss, there will be problems, but as many people have already only got DECT phones, it is arguable that most of us have already made ourselves vulnerable to these problems.

[goslow]

The oft-mentioned alternative when power cuts are discussed on the 'Home Phone' forum in regard to 21CV landlines is to 'just use a mobile' but, from my tests yesterday, the mobile network stopped working too (for ordinary calls and data).

Presumably the 999 functions of the mobile network would still have worked. For those with older family members, who might want some help or reassurance during a power cut (especially one which went on for several hours), there was no practical way to get in touch for those groups (who probably could not use text messaging under such circumstances, if at all).

There has also been a few topics on 'Home Phone' from those with medical/care alerts (which dial a general call centre number) who may also have run into difficulties as those devices (dialling general landline numbers) presumably would also have failed to work, even via the mobile network.

I'd be interested to know, from any of the regulars on the forums who are from within the industry, whether the fact that the mobile network ceased working for all but texts was actually by design during a big power cut (to prioritise emergency calls etc.) or simply that the mobile network is not that resilient and if the area of the power cut is big enough, then the mobile network stops functioning for normal communications.

[Roger_Gooner]

The vast majority of power cuts cause few problems as they last for under an hour, and the ones which I've had in the past several years lasted for a few seconds at most. For those who are at risk because they are reliant on their landline OFCOM's guidance is that providers should enable, free of charge, access to emergency organisations for a minimum of one hour.

[goslow]

Yep, well aware of that and it's true but yesterday's event went on for 3 hours for some and the mobile phone network stopped working during that time apart from intermittent texts. The bit I'm interested in really, is did the mobile network stop working by design during a big power outage or did it stop because it was not resilient to cope and still handle normal voice and data traffic during a widespread power cut.

The very vulnerable being able to summon emergency services via 999 is one thing but those who were not at a 999 need of help would not have been able to ask friends or family for assistance during the outage.

[newapollo]

Hi @goslow 

A very interesting thread and valid research/questions.

Have you contacted EE regarding the mobile signal at the time, and if so have you received any response back?

It would be an interesting survey to draw a compariosn by asking neighbours/friends if they experienced any issues during that period and which non VM networks they were on for landline, whether they were on Digital Voice,  and also any mobile issues detected on non EE mobile networks.

[goslow]

My research (such as it was!) might end up being confined only to the time spent whiling away the hours of near-darkness during the power outage!! 😁 but will have to do a bit more digging for some more local info.

Will certainly have to ask some other people on different networks if they had any issues. Info from the EE status checker just says "We recently fixed a problem in <postcode>. Our engineers have fixed a problem here. It should all be working again now. If you're still experiencing problems, let us know." Could well have been an EE-specific problem.

After an hour or so, I went for a walk around the block to try to see the extent of the outage. Everything was out apart from just a very few houses which appeared to be functioning normally (which was also quite interesting). I imagine some may have had access to backup supplies such as battery storage linked to solar power etc. My guess is that such power cuts will only become more commonplace in the future.

[nodrogd]

I do believe that some cell towers have a UPS backup. Whether all do or not is another question. It could also be call “saturation”. With everything else off in the house & boredom setting in, what is the first thing most people will do? Usually phone a friend.

With regards to some houses having power & some not. This could be down to the failure only taking out one or more phases of the High Voltage line feeding the local transformer, or a partial failure of the Low Voltage distribution. Properties should be balanced between the three 240v phases on the Low Voltage transformer outputs, so if only one phase was left operating only around 1/3 of the houses would remain on supply.

[goslow]

Good points nodrogd. I think the issue was more widespread than I first thought (seemingly a big part of SE England)

https://www.bbc.co.uk/news/uk-england-beds-bucks-herts-60869501

https://www.express.co.uk/news/uk/1585918/UK-power-cut-Suffolk-Cambridgeshire-Hertfordshire-Bedfords...

so I think it was odd for anyone to have had any power at all (probably less than 5% of the properties I saw in the neighbourhood had any kind of lights on).

I wondered whether the risk of 'saturation' might have resulted in the mobile suppliers (automatically or otherwise) invoking some kind of blocking procedure specifically to allow 999 emergency calls to get through and avoid saturation. I have since read O2 was also affected as well as EE.

[japitts]

Battery backup on mobile networks is hugely complex, and often on a site-by-site basis.

Street furniture type sites rarely have any BBU, major hub sites will usually have BBU for the comms kit but not necessarily the radio side.

In short, mobile networks are as prone to power-outages as any other electronic kit.

Emergency calls do get priority on a congested site, as do users of the new "Emergency Services Network" where discussion of EE is involved.