Updated from 3:11 p.m. EDT Time Warner Telecom ( TWTC), a communications service provider owned in part by Time Warner ( TWX), on Friday announced plans to purchase most of the assets of GST Telecommunications for $690 million in cash. Time Warner Telecom, based in Littleton, Colo., said it has agreed to buy almost all of the debt-laden company's assets, excluding most of GST's Hawaiian assets and some residual cash balances. GST Telecommunications, a telecom carrier based in Vancouver, Wash., filed for bankruptcy protection on May 17. Its assets were auctioned off in open bidding this week. Pending regulatory approval, Time Warner Telecom said it expected the transaction to be completed by the end of the year.