Here is an application that could save your evening or possibly your life. It is based on text messages, works with any cell phone, not just smartphones and it does not rely on an Internet connection. The service is called Kitestring.
A person sends Kitestring a text with time period like '30m'. In
30 minutes, Kitestring will send back a check-up text and you have
five minutes to respond with an 'OK'. If you do not reply on time,
Kitestring sends an alert to your designated emergency contact. It
might be handy to set before blind dates, traveling alone, or for
The basic service is free with eight uses per month with one
emergency contact. A paid version offers unlimited uses and
contacts as well as with a recurring check-in mode and customized
The recurring check-in might be useful for people with medical
conditions and/or who live alone. For instance, you can have it
check in on you once or twice a day. A pleasant way to be reminded
to let someone know you are OK, without the need for a call. Using
this service can mean no call is good news.