Eversource could be facing big fines after last summer's Tropical Storm Isaias left more than half a million people in the dark - some for more than a week.

Connecticut Attorney General William Tong is calling on the utility to pay up.

Tong asked state regulators to fine Eversource, saying its "communications systems...were at times non-existent."

"Their website failed, it went down. Their texting apps, their call center," said Tong.

It wasn't just customers who couldn't reach Eversource. Tong says police and fire departments got busy signals trying to report downed power lines.

At hearings this summer, public officials piled on the complaints.

"When I spoke to an Eversource supervisor, I was hung up on," said state Rep. Mitch Bolinsky.

Eversource says it can improve communication with towns, but is denying claims emergency response could not get through.

"Police and fire did not get busy signals. Police and fire had a direct line into our company," said Craig Hallstrom, Eversource regional operations president.

As for Connecticut's other major power company, Tong called United Illuminating's response "generally adequate." In fact, "UI's communications systems actually outperformed previous storms," said Tong.

Connecticut’s Public Utilities Regulatory Authority are still deciding whether to penalize Eversource and UI. They plan to release a DRAFT decision around March 19.

"We thank the Attorney General for his vigorous advocacy in PURA's ongoing investigation into Eversource's and UI's preparation for and response to Tropical Storm Isaias," said PURA chair Marissa Gillett in a statement. "A draft decision in this matter will be released for comment on or around March 19, followed by a commissioner vote on the final decision scheduled for Wednesday, April 28. If PURA's final decision concludes that penalties are warranted, PURA will move immediately into a penalty phase of the proceeding."