It is hoped this will give parents flexibility to balance their jobs with activities such as the school run, their children's holidays and unplanned emergencies.
The trial, which will be piloted at O2's stores at The O2 in Greenwich, Edinburgh and St Albans, appeals primarily to parents who wish to work, but need additional flexibility for family and household tasks. Each participating group that shares their shifts has the flexibility to agree changes at any time.
The roles will primarily target parents with the potential to grow their careers at O2, with scope for increased hours and a full-time role if and when the time is right for them.
Ann Pickering (pictured), HR director, O2, said: "We recognise that family comes first, and we want to make it as easy as possible for our people to be there for their family when they need to be, whilst managing their job responsibilities. The importance of work life balance in determining our people's loyalty to O2 and their levels of job satisfaction is integral to us offering our customers the best service possible.
"O2's most recent employee survey indicates that flexibility of working hours is a key issue for parents. With many of O2's 11,500 strong workforce juggling children and employment, the Working Families' Contract has the potential to overcome these barriers."
Carrie Longton, Mumsnet co-founder, added: "We want companies and organisations to be loud and proud about their family friendly policies and credentials. Through our Family Friendly programme we can recognise companies that are listening and improving. O2's Working Families' Contract is a great step forward in helping parents juggle work and family."
The Working Families Contract has been developed with support from Mumsnet as part of their Family Friendly programme. Mumsnet is working with a number of UK businesses, including O2, to help improve their customer services and parent-friendly employment practices.