Ethiopia is now in its fourth day of an internet blackout.
But whereas on Tuesday and Wednesday the service had resumed temporarily, it did not return after it had been shut down on Thursday.
The text message service also remains blocked.
The state-run monopoly phone provider Ethio Telecom has told BBC Amharic that it “did not have a mandate” to comment on the outages.
The closure of the services coincides 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.
On Wednesday, the state broadcaster ETV reported that four students had been caught cheating after sending each other text messages.