How do the Cell phone jammers at the State of Nation Address work?

How do the Cell phone jammers at the State of Nation Address work?

how do the Cell phone jammers at the State of Nation Address work?

All communications broke down at the South African President State of the Nation Address 2015. Literally.

Reporters on the scene were live-tweeting as the honourable-guests arrived outside the building, but as soon as they entered Twitter became still for a little while. Twitter wasn’t offline, but the reporters were as the government used cell phone jamming technology to block cell phone signals from inside (allegedly speaking of course). The lull in Tweets became a Twitter storm as outrage poured in from the both the Tweeting public and reporters alike.

According to Independent Communications Authority of South Africa, no device may jam a cell phone signal and as such signal jamming in South Africa is illegal. A little legal fact that didn’t seem to stop the authorities.

It wasn’t very long before members of parliament realised that they too had no cell phone reception and began chanting “Bring Back the Signal”. A BringBackTheSignal hashtag quickly circulated on Social Media reached over 1.2 million unique people and had almost 4 million impressions:

Bring Back the Signal

Not South Africa’s finest hour in terms of freedom of expression…

How does cell phone jammer work?

When we switch on our mobile phones, they connect to the nearest cell phone tower. As we move around the cell phone signal is handed over to the next cell tower. We have “dropped calls” when this isn’t handed over correctly, or the tower we are connecting to is already at maximum capacity. As the phone disconnects from the tower, it immediately tries to reconnect which is why you see on your screen the signal meter dropping to zero and then immediately connecting again. Data uses the same methodology to get from your phone to the tower and then out onto the internet.

A cell phone jammer works by transmitting a signal on the same frequency as the cell phone towers. Think of this as someone standing in a room on one side talking to someone on the other side of the room. A cell phone jammer is like placing a screaming child in between the two people essentially drowning out their conversation until they can no longer hear each other and they stop talking.

Jammers are the screaming child. They continuously broadcast signals so that they interrupt the cell phone from making contact with the tower.

For this jammer to work, it needs to be powerful enough to broadcast its signal and be “louder” than the towers just how loud the jammer is depends on how powerful it is. Hand held jammers are usually covert devices disguised as everyday objects such as cigarette packs or books. These have a limited range and therefore they only jam phones that are close by. The overt jammers are installed and mounted with large antennas and can jam phones on a larger scale.

Why are there cell phone jammers ?

Jammers were originally used in the military to block communication between the enemies and their head quarters. This jamming technology had to evolve from blocking field communication devices to blocking cell phones when the military realised the enemy used mobile phones.

Jammer can be helpful in places such as prisons where the inmates should not have cell phone equipment but smuggle them in. There is also cell phone jamming paint that could be used inside school or university exam rooms so that cheating via cell phone doesn’t take place.

SONA situation

By blocking the cell phones inside the building, all that happened was that there was a delay in sending out the tweets. Phones still worked. Video was still being recorded. Tweets were typed and saved into Draft. As soon as a signal was accessible, all the content was simply uploaded.

So what was really achieved ? Nothing.

Jammers were like E-Toll – received all the wrong kind of attention. Ultimately the people’s voices (and tweets) were louder than the jammers.


*headline image from

Liron Segev - TheTechieGuy

Liron Segev is an award-winning blogger, YouTube strategist and Podcast. He helps brands tell their stories in an engaging and real way that regular consumers can relate to. He also drinks too much coffee!

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