The Philippines’ de facto messaging standard is still text messaging. Most Filipinos have at least one phone and could be reached by relatives, friends, schoolmates and officemates via text message.
While not all may have data subscriptions to be able check extreme weather news on Twitter or the websites of PAGASA and Project NOAH, the government knows for a fact that it could easily, cheaply and quickly send text messages to citizens.
Enter Republic Act 10639, otherwise known as the Free Mobile Disaster Alerts Act, which was enacted into law on 20 June 2014.