Every mobile user in the UK will receive the same text alert from the government urging them to stay at home for the first time.
The message reads: “CORONAVIRUS ALERT: New rules in force now: you must stay at home.
“More info and exemptions at gov.uk/coronavirus. Stay at home Protect the NHS. Save lives.”
The government trialled an emergency alert system in 2014 but it was never put into practice.
The lack of an emergency alert system means some customers will receive the message later in the day while others have already received the text.
Instead the government has had to work with operators to send messages directly to phone users, as has already happened in countries such as South Korea and the Netherlands.
The trials run by the Cabinet Office were carried out with three of the UK’s biggest mobile network operators testing three different technical approaches.
They experimented with sending a text message to all handsets in a defined area and using location-based SMS messaging to target numbers in a specific area.
The news comes after Prime Minister Boris Johnson made a televised address to the nation on Monday evening announcing strict new stay at home measures.
Mr Johnson said people will now only be allowed to leave their homes for very limited purposes and that police will have the power to enforce the latest restrictions.
Despite the announcement travellers reported packed carriages on the London Undergound.