The theft of a section of BT submarine cable disrupted phone services for more than 9000 homes, police said.
Northern Constabulary is appealing for information after the cable was cut and stolen from the shoreline at Stromeferry, Ross-shire.
Police said the theft happened between 3pm and 5pm on Thursday, June 7.
Officers want to speak to anyone who may have seen a dark van in the area around these times.
They are also keen to trace a female who was believed to be walking in the area around the former Marconi Yard, and may have approached a male nearby.
BT Openreach is offering a reward of up to £1000 for information that leads to a conviction.