The Communication Workers Union (CWU) welcomed assurances over redundancies today after Sky agreed to buy 500,000 O2 customer accounts.
Sky will pay O2 owner Telefonica £180 million for the O2 and BE consumer broadband and home phone businesses.
CWU deputy general secretary Andy Kerr said: "We have pushed O2 hard on the question of jobs and have received assurances that there will be no redundancies at all.
O2 said that it will redeploy affected staff into other roles after a transitional period in which they continue to carry out work on broadband.
"We will be there at every step of the way to ensure that CWU members are treated fairly and retain their jobs," Mr Kerr added.
The deal is due to complete in April and will close the gap on market leader BT, as well as place Sky ahead of Virgin Media and TalkTalk.