The thieves struck in the Magherawarden area of Fanad in recent days.
Customers have been told they will now be without landline phones for a number of days while the wires are replaced.
It is suspected that the gang used machinery to cut the wires which contain valuable copper.
It is suspected that this is the FIFTH such theft this year.
In January thieves took their lives in their own hands when ESB lines carrying 20,000 volts were stolen in the Knockalla area.
Garda in Milford are investigating the latest theft.
A local community source in Fanad said the thefts of phonelines had caused a lot of hardship and isolation for elderly people in the elderly.
“A lot of people, especially elderly people, in this area do not use mobile phones are are dependent on landlines.
“They have been told it will be a few days before phonelines are restored and that’s dificult for them.
“The fact that it’s happening so often around here is the things that’s so annoying. You would think they would have an idea who it was by now,” he said.