71250 - this is the number which will deliver text alerts to people if there is a major emergency nearby, be it a fire or a terror attack.
The free, one-way SMS will be sent almost immediately to all mobile phone users in the vicinity of the emergency, regardless of subscription type.
The SMS public alert system, already adopted by StarHub, will be available to subscribers of all telcos by the end of next year. Tourists using international roaming will also get the messages.
Launching the system yesterday, the latest in a series of recent anti- terror measures, Deputy Prime Minister Teo Chee Hean said that in the event of an emergency, there needs to be more than one channel of communication to "warn residents about danger, and give them appropriate advice on how they can and should respond".
"Some of us may still not be familiar with apps or we may have older 2G phones which don't support apps," he added in a speech at an emergency preparedness event held beside Pasir Ris MRT station.
The system will be activated to send alerts during emergencies such as bomb blasts, gunman attacks, big fires and major public order incidents like 2013's Little India riot.
When such events occur, the Ministry of Home Affairs (MHA) will demarcate an area around the site. Telcos will then send the alert to customers who are in the area.
Similar alert systems are used in Europe, Australia, Japan and South Korea.
The United States, which has had its system since 2012, used it in the wake of a series of blasts in New York and New Jersey last month to seek help in finding the suspect.
Singapore's alert system comes as the Government ramps up security against terrorist attacks.
Last month, Prime Minister Lee Hsien Loong launched the SGSecure movement, which aims to get all Singaporeans involved in the fight against terror.
It includes the SGSecure app, which provides alerts similar to the SMS system but requires an Internet connection.
The app, which has been downloaded more than 25,000 times, also allows users to notify the police of incidents or request help.
Since June, the police have trained Emergency Response Teams, comprising police land division officers, in counter-assault skills. The teams are armed with HK-MP 5 submachine guns and will be the first line of response to a terrorist attack.
Yesterday, Mr Teo, who is also Coordinating Minister for National Security, said that StarHub is the first telco to have implemented the SMS public alert system. Singtel and M1 will follow suit by end-2017.
The system, on trial since August, was used for the recent fires at CK Building and in Jurong West Street 41. StarHub users near yesterday's event received an alert telling them not to be alarmed by a simulated attack by gunmen.
MHA said that it decided on a phased approach as there would be significant work needed to integrate the system with the telcos' infrastructure.
MP Louis Ng, a member of the Government Parliamentary Committee for Home Affairs, said that some elderly people in his Nee Soon ward do not have Internet access on their phones, but use text messaging instead. "It's important to be able to reach out to this group," he said.
Separately, the coordinated response of public agencies to a terror attack will be put to the test in an exercise tomorrow and on Tuesday.
It will be led by the police and include the Singapore Armed Forces and Singapore Civil Defence Force.