Wireless carrier Sprint will lay off an undetermined number of its workers as part of a cost-cutting program announced Thursday.

A regulatory filing says the Overland Park, Kan.-based company began drawing up layoff plans last week. A Sprint spokesman says the company's managers are still reviewing how many jobs they will need to cut.

More details could emerge when Sprint Corp. reports its fourth-quarter earnings on Feb. 11.

The purge is expected to be completed by the end of June.

About 39,000 people work at Sprint, the third-largest U.S. wireless carrier.

The cutbacks may be substantial, based on how much Sprint is preparing to pay in severance and other benefits.

Sprint expects to absorb a $165 million hit in the fourth quarter and may take more charges in the future.