Silent Alarm is a free must have Android app for everyone. In an emergency situation, it could save your life.
When you dial out to an emergency number (eg. 999, 112, 911), but for whatever reason cannot talk to the operator, Silent Alarm will automatically get your location and notify up to five of your pre-selected contacts. The message recieved by your contacts will have your latitude and longitude, and approximate address. Your contacts can then either call the police for you, or come to assist you personally.... More Info »
After the first message is sent, depending on your preferences, a new update message will be sent to each of your pre-defined contacts either every 30 seconds, 1 minute, 2 minutes, 3 minutes or never. Each time with your updated location.
In the preferences you can stop Silent Alarm listening for your emergency calls, eg, for when you don't want to inform your contacts that you need emergency assistance. By default, the message prefix (the start of the emergency SMS) is "!SILENTALARM! PLEASE SEND POLICE HERE IMMEDIATELY: ". You can also personalise this.