Qwest and members of its largest employee union are still talking, after facing a midnight deadline on Sunday, for coming up with a new contract.
The contract covering 25,000 workers in more than a dozen states is set to expire at midnight.
Union officials say formal talks have been recessed and negotiators have split up to discuss separate issues in hopes of averting a strike.
Qwest officials say the company continues to bargain in good faith but decline to discuss specifics.
The company's mandatory overtime policy is a key sticking point.
The current contract calls for a maximum of eight overtime hours a week and the union says Qwest wants to boost that to 16.
Union members are being asked to start gathering at the Communication Workers of America headquarters in Denver at 6:00 Saturday night.