Reverse 1-1-2

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Reverse 1-1-2" – news · newspapers · books · scholar · JSTOR (March 2021) (Learn how and when to remove this message)

Reverse 1-1-2 is a public safety communications technology used by public safety organizations throughout the world to communicate with groups of people in a defined geographic area. Reverse 1-1-2 allows authorities to rapidly warn those in danger, directly through their mobile phones.

The system uses preferably Cell Broadcast technology to deliver predefined emergency messages. Examples of successful nationwide reverse-112 implementations can be found in Japan, Taiwan, South Korea, United States, Canada, United Arab Emirates, Saudi Arabia, the Philippines, Oman, Romania, the Netherlands, Greece, Chile, Peru, China, Russia and New Zealand.

A possible alternative to Cell Broadcast is Location-Based SMS systems (LB-SMS). The location data accuracy of location based SMS is limited to the size of the mobile cell this is typically between 3 and 15 km (2 and 9 miles). LB-SMS needs to determine first the identities of the subscribers (cell phone numbers/MSISDNs) present in the target cell area(s) and in a second step it needs to send the SMS messages to all of the cell phones attached to specific cell towers. Location based SMS has been chosen to deliver public safety alerts in Sweden, Australia, Norway, Singapore and the Indian states of Odisha and Andhra Pradesh who have implemented multi-channel Early Warning Dissemination Systems (EWDS) as part of the National Cyclone Risk Mitigation Project