Ohentse Toto, Facebook asked:
Why is it that when u don't have signal but can communicate to emergency numbers? Why can't cellphone use that channel?
We put this question to Professor Mark Beach, Bristol University...
Mark - In a mobile phone network we have what we call broadcast control channels, and the traffic channels that the general communications go out on. The broadcast control channels can also carry the emergency calls and your SMS messages. So yes, it does happen that sometimes you've only got emergency cover and not general call cover.
Also remember that an emergency call is treated differently by the phone. In calling an emergency number it will connect with any operator signal it can find, irrespective of your own operator settings, as these calls are not billed. Thus if you have no signal from your network it will use a network it is normally not allowed to connect via if the signal is stronger than the minimum allowed to get a link with the cell site nearest to you. SeanB, Tue, 5th Apr 2011