Ethiopia has shut down its text messaging service in a move that is coming as part of a break in internet access in the country for more than two days now.
The move is targeted to coincide with nationwide exams.
There has been speculation that the internet blackout is aimed at trying to stop people cheating, but this has not been confirmed by the authorities.
Ethio Telecom, the country's monopoly internet provider, told BBC Amharic that it has "no mandate" to comment on this issue.
On Wednesday, the state broadcaster, ETV, reported that four students had been caught cheating after sending text messages to one another.