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

Smartphones have become such an integral part of our lives that people who don’t yet have one often find themselves in situations like these:

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For a smartphone owner, the most annoying feeling in the world – other than the battery dying just as you receive a long-awaited text message – is having no network coverage on your phone! People do all kinds of unusual things to find service, and some truly freak out like it’s the end of the world when they don’t see those network bars in the top corner of the phone’s display.

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During those situations, namely when there’s no network coverage on your phone, your phone has probably informed you (almost to the point of being rude) – “No Network. Emergency calls only.”

Wait a minute! Isn’t that message an oxymoron? How could you make ‘Emergency calls’ when you don’t have network coverage on your phone in the first place?

Why Do You Need Network Coverage Anyway?

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Photo Credit: itestro/Fotolia

Network towers are an absolutely essential component of the wireless calling process. Let’s suppose that you want to call a friend; the moment you press that green (or whichever color it is on your phone) ‘call’ button, your phone emits a signal for the nearest network tower to catch. From there, the signal goes through a series of steps to arrive at another tower (which is nearest to your friend). Finally, the signals from the tower are received by your friend’s phone and voila! The two of you are talking!

The bars in the top corner of your phone signify the ‘usable strength’ from your network service provider. When the bars disappear, it means that the network coverage is not strong enough to make calls, send texts and so on. If that’s true, then how can you still make those ’emergency calls’?

Exploring the Mystery of Emergency Calls

Like many people, you may think that there is some kind of tricky machinery fitted inside your phone that enables it to make emergency calls, but unfortunately, that’s simply not true.

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As mentioned earlier, cellphones 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, but your access to it will be limited, hence the ’emergency call’ restriction.

Therefore, in the absence of a strong enough network coverage of your own service provider in your area, 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.

What if your SIM card is dysfunctional?

In some western countries (like the United States and England), people can connect with an  emergency number (e.g 911 or 999) even if their SIM cards are not in proper working order. Note that it’s not the SIM card, but rather the antenna in your phone, that gets you connected to a network tower. A SIM card only has the phone number and carrier info, so it’s not essential to make an emergency call. In such cases, since the SIM is dysfunctional, the emergency service center does not get the caller ID or the location of the caller, but the call can be connected.

What if there is absolutely no network coverage?

No network

If you happen to be in a place where there is absolutely no network coverage from any service provider, then that’s just bad news. Since there is no network tower in the vicinity that can receive and transmit the signals coming from your phone, your phone becomes completely ineffective.

Given that fact, for people who travel to remote locations to explore hinterlands and unknown places, it’s absolutely necessary to have communication backup (in the form of satellite phones or radios) in the case of dire situations that require immediate assistance.

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If a visit to the jungles of the Amazonian basin is in the cards for you, ensuring that you have the necessary communication options in that dense green paradise is a very wise choice.

References

  1. Leading Britain’s Conversation
  2. Instructables

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