Due to not registering in the national digital identity database (NIN) Nigeria has blocked a total of 73 million mobile phones, which has prevented them from making outgoing calls.
Constance Chioma calls her son every morning to make sure he's safe while studying in northeast Nigeria, which is ravaged by Islamist rebel attacks and armed kidnappings.
She couldn't get through earlier this month.
She later discovered that her SIM card was one of 73 million - more than a third of Niger...
