Mobile and telecoms firm O2 is to cut its workforce by 120.
Telefonica Ireland, which operates the brand in Ireland, said it was making the redundancies to reduce costs and drive efficiencies.
The company said: "Telefonica Ireland has taken this difficult decision in order to directly deal with the ongoing challenging market conditions, including a fiercely competitive telecoms sector.
"In responding to these challenges, the company is making changes to processes and operations to drive greater efficiency while maintaining the service it delivers to customers."
The company employs 1,100 people in Ireland.
Telefonica also said the cost saving would ensure that O2 would be able to offer competitive prices to consumers and invest in next generation products and services.
The company said it made the decision on redundancies following a comprehensive review of the business which identified a need to reduce its cost base including employee numbers.
It is the second blow to workers in the telecoms sector after communications giant Eircom warned in a business plan that it could cut its workforce by 1,000 as it secured court protection to restructure its debt.