This links to a short video on the use off 112 as an emergency contact from a mobile. It has the benefit that it is not limited by the contract with your provider, so as it is an emergency number any carrier will be used and irrespective of funds on your account..
http://www.youtube.com/watch?v=XPZv_8dABfU&feature=youtu.be
Many thanks to Roger Cornish for this
Rgds
Kevin