The majority of cases have been reported in Cavan, Monaghan, Louth and Meath.
Gardaí are appealing for information due to an increase in telephone cable theft in the past six months.
66 incidents of cable theft were reported nationwide, with the majority of cases arising in Cavan, Monaghan, Louth and Meath.
Gardaí predict that the cables are being targeted for their copper material.
The thefts have caused significant loss to Eir, the affected telephone provider, and have also caused major telephone and internet service outages for the public.
It can take two to three days to restore phone and internet services which are impacted by the theft, most commonly in rural areas.
More than 1,500 households have been affected by the thefts in the past six months, with older, more vulnerable people being a main concern for Gardaí.
"An Garda Síochána wish to advise that works on telephone cables do not take place during the hours of darkness and that if the public notice activity on telephone cables at night they should treat this as unusual and make contact with their local Garda Station or call 999,” Sgt Michael Duffy, Crime Prevention Office for Cavan/Monaghan Division said.
"These cables are located over ground on telephone poles and following these thefts cable casings are often left behind.
"Where a member of the public observes discarded casings they are urged to also make contact with their local Garda station as this information could be beneficial to this investigation,” Duffy added.
An Garda Síochána is also liaising with metal dealers and are appealing to them to make contact with An Garda Síochána if they are approached to buy significant amounts of copper cable or copper in unusual circumstances.
An incident room has been set up at Carrickmacross Garda Station and anyone with information can make contact with them on 042-9690190 or via their local Garda Station.
