In some countries, text messages can be used to contact emergency services. In the UK, text messages can be used to call emergency services only after registering with the emergency SMS service. This service is primarily aimed at people who, by reason of disability, are unable to make a voice call. It has recently been promoted as a means for walkers and climbers to call[27][28] emergency services from areas where a voice call is not possible due to low signal strength. In the US, there is a move to require both traditional operators and Over-the-top messaging providers to support texting to 911.[29] In Asia, SMS is used for tsunami warnings and in Europe, SMS is used to inform individuals of imminent disaster. Since the location of a handset is known, systems can alert everyone in an area that the events has made impossible to pass through e.g. an avalanche. A similar system known as Emergency Alert is used in Australia to notify the public of impending disasters through both SMS and landline phone calls.These messages can be sent based on either the location of the phone or the address to which the handset is registered.