What impact will Storm Ciarán have on mobile operators?

A library image of a cell tower / mobile mast. Credit: PA

Words by ITV Meridian Journalist Harry Acton.

As Storm Ciarán is set to bring disruption to the South East of England, households are being warned of disruption to power supplies.

Gusts upwards of 70mph could be likely, with coastal areas particularly at risk.

These could bring down power cables and disrupt supplies to communities, and distributors are urging people to report any outages to them.

Will my phone have signal?

In the short term, yes it will.

Mobile masts operated by all of the UK's big four networks have a battery backup on site, which is usually designed to cope with a small power outage.

These batteries can supply power for a limited amount of time and can be anywhere from 45 minutes to six hours.

Some of the more major cell towers, think those big ones you see on hilltops, may have a diesel generator backup, meaning you may have a signal for longer.

A Vodafone mast in a rural location. Credit: Vodafone UK

If I have a signal, is it guaranteed to work?

This is where it gets interesting from a technical perspective, during periods of bad weather you may experience moments where your phone hangs - when a web page won't load, or you can't make a call.

This is due to congestion on the network. As domestic supplies fail, more people turn to their phones, which puts strain on the nearby masts.

Each mast has a backhaul, whether that is fibre to a nearby exchange, or via a microwave dish to another cell tower.

These can be overwhelmed, meaning you may experience periods where your phone appears to not be working.

If the backhaul or transmitters are damaged it could mean one mast isn't working, forcing more devices to use a different tower. Or you may have no signal at all.

What about my landline?

For those of us who still have a trusty landline phone, some of these will work, even if the power is out.

BT is currently in the process of moving the British phone network to Voice over IP (VOIP), which means some of us are now required to plug our phones into our broadband router, rather than any old socket in our homes.

Some, particularly in rural areas, won't have been moved over yet - which means if they have a wired landline, not wireless, they can probably make a call as long as there is no damage to the telecom cables from the exchange to their property.

If you have a wireless handset, these require power to work, so you're out of luck.

More than two million people have landline-only contracts with BT Credit: PA

What do the operators say about this?

One of the world's biggest operators, the Berkshire-based Vodafone group, says its sites will have battery backups in case of power failures.

Most Vodafone masts will draw their power from the National Grid, and it is possible some will have their own renewable power source on-site.

In a handful of cases, such as with temporary masts, power will instead be provided by a diesel generator the company says.

The company doesn't say how long its batteries last, however.

Its masts tend to have cables, traditionally copper but now far more likely to be fibre optic, connecting it with other masts and the rest of the Vodafone network in the UK. 

As long as these are not damaged the mast would still function in case of power failure, until the batteries die.

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