It is hoped many of the cuts can be filled by voluntary redundancies
The publisher of the Yellow Pages in the UK, Reading-based Yell, has announced it is planning to cut 1,300 jobs over the coming year.
Up to 350 redundancies will be lost in the UK out of a 3,860 workforce as the firm looks for £100m of savings.
Yell's two sites in Reading and its Slough office are "included in the proposal", a spokeswoman said.
The Communication Workers Union (CWU) said voluntary redundancies and redeployment should be considered.
Andy Kerr, CWU deputy general secretary, said a meeting with Yell over the possible job cuts had already been held.
"While job losses are always a last resort, CWU and Yell are jointly committed to achieving these job reductions by the use of the recently agreed restructuring policy which emphasises the use of voluntary redundancy and redeployment," he added.
The announcement came as Yell reported a 6% rise in half-year revenues to £1.03bn and pre-tax profits of £118.3m, against £121.6m a year on Tuesday.
Chief executive John Condron said the job cuts were in readiness for continued tough trading conditions.
He added: "Global economic trends show no sign of improving; therefore, we are actively working on further cost reduction programmes that will primarily benefit next year."
Mr Condron said he hoped the efficiency drive meant Yell would be able to maintain investment in its products, including Yell.com.