Eir is opening a voluntary redundancy scheme that could see up to 140 staff leave the organisation.
It is expected that most of the redundancies will come from the company's networks division and Eir Sport.
Last month Eir confirmed the sports channel is to cease broadcasting later this year following an in-depth review.
"eir has opened a voluntary redundancy programme targeted towards employees in specific areas of the business," Eir said in a statement.
"This programme has been opened due to changing operational requirements."
The telecoms company currently employs around 3,500 staff.
"Any employee who decides to take voluntary redundancy will leave eir later this summer," the company added.
In May, the company said its third quarter results were in line with expectations.
The company said its revenue fell by 3% to €299m as income from voice calls and its sports content waned.
Eir said its broadband and mobile customer numbers grew in the three months to the end of March, with the increase in mobile customers driven by its low cost GoMo service.