I recently went on holiday in rural New Hampshire on the east coast of the United States. During the week my daughter had an important call scheduled. Unfortunately it turned out we were travelling in the car at the time on the way to a nature reserve.
When the mobile rang, my daughter answered. All was well for the first two or three minutes, but then she lost the call. The person called back shortly after and they were able to talk another couple of minutes. But the call was lost again.
New Hampshire is very mountainous. The people there are also very protective of their natural habitats, making it difficult for mobile carriers to put up towers in rural environments. As a result, the network coverage is patchy as you move away from the central part of the state.
When we arrived at our destination, we noticed that we had only limited mobile service – just one bar on an extended network which explained the dropped calls. Then we noticed there was a text message waiting. My daughter replied and continued having a text message conversation rather than a voice call.
Afterwards she tried to get email, but it wouldn’t load. The signal just wasn’t strong enough.
So why did the text messages make it through, but no calls or emails?
The reason gets a little complicated, but the short answer is a text message uses less bandwidth than a voice call. Email can use less bandwidth than a voice call too, but it depends on how many you have, what format, and if there are images.
So in areas with limited service, it’s more likely that the lower bandwidth text message would get through. That’s great news for emergency services using text messaging or anyone that is looking to have a high real-time delivery rate regardless of location.
Of course there are all sorts of places where mobile coverage isn’t great. There are also situations where mobile communications are stressed and voice calls can’t be completed. Natural or man made disasters are guaranteed to overload mobile networks that may also be damaged. If you want to read an interesting account of such an example, take a look at this blog on Crackberry.com. The author recounts what is was like to be in New York City on 9/11 when the twin towers were attacked. He goes into a bit of detail about the technology used on mobile networks and why text messages (especially on the Blackberry network) were able to get through that day when voice calls failed to connect.
We have our own version of that story here at fastsms too. On the morning of the 7/7 bombings in London back in 2005 we were contacted by certain emergency services within minutes of the terrible event. We were informed that “an emergency” was taking place and that the conventional mobile network in the capital was overwhelmed. So it was the fastsms network that was used throughout the day to coordinate rescue services. A most poignant underlining of the resilience of the network.
Is there any particular place where you have issues with voice calls but not texts?