Harrogate-headquartered Amvoc, which also has offices in Leeds and Manchester, has entered administration.
Ceasing trading with immediate effect, up to 450 jobs have been lost.
According to Aticus Law, staff at the telemarketing company received an email at around 10pm on Tuesday night, informing them that all of the offices were closed with immediate effect and telling them not to turn up to work in the morning as they no longer had a job.
It is said that some staff who didn’t see the email turned up to work on Wednesday morning, but were unable to get in as the Amvoc offices were locked.
Aticus Law is now looking to help Amvoc staff by making a claim for a protective award, where they could claim compensation of up to 90 days’ pay.