The authority of Zimbabwe thinks that having 3 mobile gateway provider is too much, it is a hazard to national security. In CNet news they say,
"We want to listen, to make sure the nation is safe. If we liberalize the gateways then it means there would be a group of people who would communicate without our knowledge,"
(Link) and (Link)
A good example for countries that wanted to restrict liberty locally. That makes me wonder is our communication moniter here? I think I can never find out.