A rail union has threatened to walk out over working agreements of control room staff.
The Transport Salaried Staff's Association (TSSA) has warned strikes could take place for its members who work for South Western Railway.
The two sides failed to come to a resolution after disagreeing over the "imposition" of changed working arrangements.
Gareth Theobald, TSSA organiser for SWR, said: "This isn’t merely a shift in working patterns, it’s a stark deviation from well-established norms and we urge SWR to return to the negotiating table without delay to resolve this issue.
"SWR should be in no doubt that if staff need to take action, then trains will come to a stop."
Last month, train drivers from five operators voted in favour of further strikes, meaning union Aslef now has action ongoing against all 16 companies where there is a dispute currently ongoing.
Union members at Chiltern Railways, c2c, East Midlands Railway, Northern Trains and TransPennine Trains workers all voted in favour of strikes, Aslef said.