Expert reveals why phone signal fails on marathon day - and how to stay connected

• With more than 59,000 runners expected at the start line, spectators should prepare for busy networks on race day^[1]
• Crowds at pinch points such as Tower Bridge, Canary Wharf, and The Mall^[2] can overload local masts, causing patchy data and delays to live‑tracking updates
• Uswitch mobiles expert Archie Burkinshaw explains why this happens and shares practical tips to prepare, including downloading offline maps, agreeing on meeting points away from the finish line, and switching to 4G for stability

With more than 59,000 runners and huge crowds expected across the capital this year for the London Marathon^[1], experts warn mobile networks could come under pressure at key hotspots such as Tower Bridge, Canary Wharf, and the finish line on The Mall.^[2]

Archie Burkinshaw, Uswitch mobiles expert, explains why networks fail at large events such as the London Marathon and his tips on how to stay connected: “On marathon day, some of London’s busiest spots can put mobile phone networks under pressure as thousands of runners and spectators try to get online at once. 

“It’s often not a coverage problem, but a capacity issue, as local masts will get overloaded by the number of devices trying to connect at the same time. This can create digital gridlock, leading to lower data, delayed live-tracking updates, patchy calls, and trouble uploading photos or messages. 

“In some cases, people may still see full signal bars, but performance can lag because the network is congested. 

“If you’re worried about losing connection, one option is to have a backup eSIM ready on another network. Most newer phones let you keep your usual number active while using the second network for data, although busy areas can affect multiple networks.

“A few quick checks before you leave can make all the difference: download maps, save tickets or travel info, agree on a meeting point, and pack a portable charger.”

Archie Burkinshaw’s top tips to beat marathon signal blackspots:

• Add a second network with an eSIM: One of the easiest fixes is to install a one-month eSIM on a different network before race day. You can get an eSIM for as little as £2.50 per month for 100GB^[3] - and most newer phones let you keep your usual number while switching your data line in seconds if your main network slows down.
• Map the blackspots: Expect congestion around Tower Bridge, Canary Wharf, Embankment/Westminster, and The Mall. Agree on a meeting point away from the busiest areas and set a fallback time in case live tracking is delayed.
• Switch to 4G if needed: If 5G feels patchy, try changing to 4G only. It can often be more stable in large crowds and may help preserve battery life. A quick toggle to aeroplane mode can also reconnect you to a less congested mast.
• Keep messages light: Use SMS or low-data messaging where possible, and avoid uploading videos in the busiest areas. Take screenshots of tracking links, QR codes, and maps beforehand so you’re not relying on live data.
• Download offline tools: Save central London offline in your maps app and pin key spots such as the start, viewing points, finish line, and your meeting place. If you’re using the official race app, remember updates can sometimes arrive in bursts.
• Power up properly: Bring a 10,000–20,000mAh power bank and charging cable. Enable Low Power Mode, lower screen brightness, and turn off background app refresh to help your battery last the day.
• Use Wi-Fi when available: Many pubs, cafés, and restaurants along the route offer guest Wi-Fi, which can be a useful fallback if mobile data is struggling. 
• Be ready to switch manually: If your phone sticks to a weak signal, try manually selecting a network before switching back to automatic mode. Even moving 100-200 metres away from the densest crowd can improve service.
• Runners z– plan to be offline-friendly: Download playlists and maps before you start, limit live uploads during the race and consider aeroplane mode with GPS enabled on your watch so your phone battery lasts to the finish.

Visit Uswitch.com for more information on mobile phone network coverage.

ENDS