TORONTO – Enterprises might be facing the prospect of one less telecom option as yet another competitive carrier filed for bankruptcy protection this week. Dallas-based competitive local exchange carrier (CLEC) Allegiance Telecom Inc. announced Wednesday it is pursuing restructuring plans under Chapter 11 of the U.S. bankruptcy code. The announcement was made on the heels of a small disaster Wednesday morning, which left Allegiance data customers in the Boston area without service for more than five hours. According to reports, a backhoe accidentally sliced through Allegiance-owned cable, cutting Internet service and some telephone service to the CLEC Technology Industry