How Can Mobile Phones Make ‘Emergency Calls’ When There’s No Network Coverage?

Cell phones require network coverage to make calls. However, if the usable strength of the mobile network of your service provider (the manufacturer/company of the SIM card that you are using) is not good enough at the place where you’re making the call, then they use the network of some other service provider whose usable signal strength is strong enough to make the call. GSM technology (most SIM cards work on GSM nowadays) is designed in such a way that you can use the network of another service provider in the absence of network coverage from your own service provider. Still, your access to it will be limited, hence the ’emergency call’ restriction. Therefore, in the absence of sufficient network coverage from your own service provider near you, your phone camps on a ‘Roaming network’ (these are those companies that have links with your own company). If the roaming network is also not strong enough, then your phone camps on the best network signal available in your vicinity, irrespective of its source company. Emergency calls can be made in this case.