Call-centre firm Eishtec is to create a total of 250 jobs at its offices in Wexford and Waterford by the middle of next year.
The Waterford-based Irish company, which provides call-centre solutions for client firms, is adding the roles after it won a contract to provide smart phone technical support in the UK for T-Mobile customers.
It will bring the total number of people employed at the company to about 1,000.
Eishtec was founded in early 2011 by former directors of the Irish arm of British telecommunications firm Talk Talk.
Talk Talk closed its call centre in Waterford in October that year, with the loss of nearly 600 jobs. It blamed the closure on the fact that many of its dealings with customers had migrated online.
Eishtec co-founder and operations director Heather Reynolds said that the rapid growth of the business has been challenging "but not entirely surprising". She said the company's mission was to "challenge the standards of service".