More talks are planned for tomorrow, and Stagecoach has warned there would be disruption to services if the strike goes ahead.
If no resolution is found, there could be a strike from Sunday November 28 until Sunday December 5 for Sheffield drivers and engineers, covering most services in the city.
The other areas would look to strike from Saturday, November 27, until Saturday December 4.
Phil Medlicott, managing director for Stagecoach Yorkshire, said: "Stagecoach has reached agreements with trade unions in the vast majority of other depots across the country, including in nearby Chesterfield, and there is no reason why an agreement cannot be reached here in South Yorkshire.
“We are committed to working constructively with our local union representatives to deliver pay proposals that are fair to our people, who do a fantastic job for us. However, we also need to ensure the long-term sustainability of the bus network for local communities at a time when passenger numbers are significantly below the level needed to cover the costs of running services.
“Strike action is in nobody’s interests. We are open for further talks with Unite in the hope that agreement can be reached to avoid this action that would cause disruption for our customers and our employees.”
Stagecoach Yorkshire employs 1,146 staff and operates a fleet of 384 buses.
Unite has been approached for comment.