Supplying, owning and operating jammers is currently illegal under the SA Telecommunications Act and could carry a R500 000 fine, two years in prison or both.

GSM operator MTN disclosed that the National Intelligence Agency (NIA) was already jamming its network in some areas. It showed examples of jamming it had encountered like at a conference at the St George's Hotel on the R21 between Pretoria and the Johannesburg airport, at the “Glass Palace” building in Bloemfontein and at a site it identified as “NIA – Pretoria”, the NIA's headquarters.

It said that in June and April 2002, it detected a jammer in use at the NIA building. While the device was operational, it recorded a sharp increase in the number of dropped calls users experienced in two adjacent cells. When it was turned off, the dropped call ratio returned to normal levels.

The St George's device caused calls to drop at more than 400 per hour while the jammer spilled interference over the fast-moving cars on the highway. The normal level is less than 20 dropped calls per hour.

Vodacom said the NIA was the only organisation it had no firm objection to having access to the technology. MTN conceded that the Scorpions and NIA might need to use jamming, but argued that its use should be limited. Cell C said the use by security forces could prove an exception but the issue would require further technical consideration.

One company representative said he had sold many units, with the police and universities among its biggest clients. And Cellblock SA, the only other jammer supplier to make a presentation, said it had never sold a unit.