The Theatre Royal is the home to Scottish Opera
Staff at two Glasgow theatres are urging customers to join a campaign to prevent the closure of their box offices.
Up to 27 posts at the Kings Theatre and Theatre Royal could go if plans to transfer calls to London go ahead.
The Ambassador Group, which runs the theatres, said the move was a necessary cost cutting measure.
Employees claim customers will suffer as they will be charged a booking fee under the new system.
They are appealing to Glasgow City Council to intervene.
The local authority owns both theatres but leases them to the Ambassador Group. It recently awarded the Group £7.2m to refurbish the 104-year-old Kings Theatre.
Ian Gordon, manager of the city's Pavilion Theatre, has joined the campaign to save the box offices. He said his theatre could also suffer.
He said: "This will clearly take away the localised box office facilities and financially penalise the Glasgow rate payer.
"Not only will they have to pay the enforced refurbishment levy but they will clearly now have to pay excess premium rates for phone calls to book tickets for both theatres.
"Surely given the level of subsidy the ambassador group receives, it's the council's responsibility to ensure jobs and services are protected."
Staff are now urging customers to write to the council and to the Ambassador Group to protest about the cuts.
The company said it plans to maintain a sales office in Glasgow and hopes to redeploy some staff.
All calls would be redirected to a central call centre which already handles inquiries for the 21 other theatres owned by the group across the UK.