An estimated 40 percent of mobile phones used in Tanzania are counterfeits and the government plans to switch off service to them by June 17 citing lost tax revenue, security and health issues, according to TanzaniaDailyNews.

Most of the phones coming into Africa from China use smuggled chips and are not licensed by the governments in the region, PCWorld reported in 2014. The phones have fake international mobile equipment identity (IMEI) codes and aren’t verified by China.

The Tanzania Communications Regulatory Authority plans to disable counterfeit phones from network service using IMEI numbers — the unique number assigned to individual mobile phones.

Tigo Tanzania, the country’s leading mobile phone company, is running a public awareness campaign to alert users ahead of the June 17 cutoff date, TanzaniaDailyNews reported.

Microsoft has urged African authorities to combat cheap counterfeit phone imports from Asia that eat into its own profits, PCWorld reported.

Counterfeit devices are taking a significant portion of the mobile phone market from legitimate manufacturers, said David Efanga, manager Nokia Care Service Channel West and Central Africa.

Brands most often faked include Nokia (Finland), Samsung (South Korea), Huawei (China), and RIM (Research In Motion), the Canadian maker of the BlackBerry, according to a report by Fitch group’s Business Monitor International (BMI), TanzaniaDailyNews reported.

The Tanzanian regulator says the move is needed to curb international organised crime and will help increase government tax revenue. The Tanzanian government also warns of health issues associated with fake mobile phones.

Since fakes are not tested for compliance with international industry safety standards, they may have harmful levels of radiation and lead, said Kenneth Halila at the Department of Electronics and Telecommunications, Dar es Salaam Institute of Technology.

“We know that the majority of Tanzanians use fake phones because they are cheap,” he said, according to a report in TheCitizen. “But they have negative impacts on their health and incomes. With higher radiation levels, fake phones can easily explode while being charged and in extreme temperatures.”

Billions of shillings are spent in Tanzania on substandard, imported mobile phones, said Innocent Mungy, head of corporate affairs for the Tanzanian telecoms authority. Tanzania has 35 million mobile subscribers and approximately 40 percent of these use counterfeit phones.

Rapid growth of mobile use in Africa has attracted dealers in counterfeit handsets, according to the BMI research. Sub-Saharan Africa saw a 13-fold increase in subscribers over an eight-year period from 35 million in 2003 to 467 million at the end of 2011.

In Nigeria, Africa’s largest telecom market by subscription and investment, there are more than 12.5 million counterfeit mobile handsets currently in use, according to government officials, PCWorld reported.

All subscribers should authenticate their mobile IMEI numbers before buying their devices, said David Zachariah, Tigo’s head of devices.

Counterfeits look like the real thing, Zachariah said. They use designs and trademarks of genuine products to deceive consumers. Genuine phones have coded identification marks inscribed in them to ensure traceability.

The Tanzanian government is pushing increased security as one of the benefits to switching off the fakes. Someone who loses a phone or has it stolen can report it to the service provider who will switch off the gadget, but customer must have a receipt.

After June, all fake and substandard or stolen mobile phones that remain on the market won’t work, the Tanzanian government said, according to TheCitizen.

That isn’t stopping dealers, who continue to order counterfeit or substandard cellphones, said Hemed Mohamed, a mobile phone trader in the Kariakoo district of Dar es Salaam. Another mobile phone trader, Leonard Matemu, said, “I sell original phones but my neighbor sells fake ones. We are all doing business.”