International GSM SIM cards for emergency calls

Is there a market for international roaming cards?

A tip for the travelling business man or for the worldwide tourists.

http://www.telestial.com/sim_cards.php

I found it interesting, that in case of emergency I could use such a sim card to have a GSM signal independent of the local GSM provider.

Because in Europe you are per country only subscribed to one company and are not allowed to roam (within your home country).

For people needing maximum rechability for emergncy calls - this could be a workaround to rent a sim card from another country - enabling the use of all GSM providers in his home country.

The term Roaming explained at Wikipedia
http://en.wikipedia.org/wiki/Roaming