Members of the Rail, Maritime and Transport (RMT) union walked out on Monday and were due to stay out until the weekend, causing travel chaos for hundreds of thousands of passengers.
Following an offer from the RMT to suspend the action if Southern returned to talks without any preconditions, Acas announced that new talks will be held today.
But Southern, part of the giant Govia Thameslink Railway franchise, said today’s service will be based on the present strike timetable, although it will try to add services.
And the RMT is pressing ahead with four days of strike action from tomorrow on Eurostar in a separate row over the work/life balance of train managers.
Eurostar has cancelled a London to Brussels train and a Brussels to London service tomorrow but expects to run a normal service on Saturday.
Further strikes are planned over the August Bank Holiday weekend by the RMT, and the TSSA union.
RMT general secretary Mick Cash said he had contacted Southern with a way forward to resolve the dispute. “Please be advised that I have now received communication from the conciliation service Acas informing me that the company will now enter into negotiations with our union officials without any preconditions,” he said.
“You and your colleagues are therefore instructed to return to work for all shifts commencing from 2200hrs tonight.”
A Southern spokesman said: “We are encouraged that the RMT has accepted our offer to resume talks at Acas and has agreed to call off its strike action.
“For our passengers’ sake we truly hope these talks will be productive and bring this long-running dispute to an end.”
Transport Secretary Chris Grayling said: “It’s important now to leave the union and the train operator to undertake these necessary talks. I hope they reach a positive conclusion as quickly as possible.”
On the Eurostar dispute, Mr Cash said: “Our members have every right to have a fair work/life balance that fulfils the operational needs of the company while guaranteeing quality time off for friends and family.”