The outage began around 3.30pm, with landline and mobile coverage throughout the Cook Islands returning within the hour.
The internet was then back up and running around two hours after it was first reported.
Chief executive Jules Maher said there had been a fault within the internal power system that caused a “ripple effect” to other parts of the network.
“Everything is restored but for now technicians are trying to work backwards to see how this occurred in the first place and at this stage they haven’t been able to identify it,” Maher said.
“We believe everything is stable but the guys are going to be monitoring it very closely.”
Maher said the network outages were not related to TCI’s preparation work for the upcoming cyclone season.
“It’s certainly something you never want to have, but it’s a reminder of how much we depend on good communication.”