SBC's (SBC) labor union says it has planned a four-day strike to show management it's serious about ongoing contract negotiations.

About 100,000 union employees in 13 states have vowed to walk out Friday and return Tuesday as negotiations stalled over a new five-year contract. So far, the two sides haven't reached any agreement on contract terms.

The SBC employees, represented by the Communications Workers of America, want job security promises, pay increases and the option to unionize jobs in the company's growth businesses, such as wireless. Among the company's proposals was a lump sum 4% pay increase for the first year, 2.5% for the following two years and 2.25% the last two years. That amounts to a roughly 14.2% increase over five years.

Union negotiators walked away from the table Tuesday and issued a 24-hour strike notice.

"We are making this a limited job action right now to drive it home to SBC that our members are serious about securing their future at SBC," said CWA President Morton Bahr in a press release.

The regulated phone business has been hit by labor strife before. After the union threatened a strike, Bell peer

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reached a last-minute agreement in September that gave 79,000 members a 3% one-time payout and an 8% raise over five years.