Glossary
What is Cell broadcast?
Cell broadcast sends one message from mobile masts to every compatible phone in an area without using phone numbers. The UK Emergency Alerts service uses it, not SMS.
Because a broadcast goes to every phone near the chosen masts, the sender needs no list. The government's alerts service says so directly: "The emergency services and the UK government do not need your phone number to send you an alert." In the UK the alerts reach phones on 4G and 5G networks; phones that are switched off, on 2G or 3G, or on wifi only won't get them.
The standard, 3GPP TS 23.041, sets a page at 93 characters in the default alphabet, with up to 15 pages in one message. The government says about 4.5 million phones received the Storm Éowyn alert in January 2025.
A business can't send a cell broadcast. Texts to a staff or customer list go one by one as SMS, which is slower to reach a whole area but tells you who each message reached and lets people reply.
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