EXHIBIT 24 POWER OF ATTORNEY Each person whose signature appears below hereby constitutes and appoints Robert S. Woodruff and Drake S. Tempest, and each of them, his true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution, for him and in his name, place and stead, in any and all capacities, to sign any and all amendments (including post-effective amendments) and supplements to this Registration Statement, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission, and hereby grants to such attorneys-in-fact and agents, full power and authority to do and perform each and every act and thing requisite and necessary to be done, as fully to all intents and purposes as he might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents, or any of them, or their or his substitute or substitutes, may lawfully do or cause to be done by virtue hereof. Signature Title Date --------- ----- ---- /s/ Philip F. Anschutz Chairman of the Board and Director July 28, 1999 - ---------------------------- (Philip F. Anschutz) /s/ Joseph P. Nacchio Chairman and Chief Executive Officer June 20, 1999 - ---------------------------- and Director (Joseph P. Nacchio) /s/ Robert S. Woodruff Executive Vice President, Chief June 20, 1999 - ---------------------------- Financial Officer and Director (Robert S. Woodruff) /s/ Jerry R. Davis Director June 20, 1999 - ---------------------------- (Jerry R. Davis) /s/ Jordan L. Haines Director July 28, 1999 - ---------------------------- (Jordan L. Haines) /s/ Cannon Y. Harvey Director June 20, 1999 - ---------------------------- (Cannon Y. Harvey) /s/ Douglas M. Karp Director June 20, 1999 - ---------------------------- (Douglas M. Karp) /s/ Vinod Khosla Director July 28, 1999 - ---------------------------- (Vinod Khosla) /s/ Richard T. Liebhaber Director June 20, 1999 - ---------------------------- (Richard T. Liebhaber) Signature Title Date --------- ----- ---- /s/ Douglas L. Polson Director July 28, 1999 - ---------------------------- (Douglas L. Polson) /s/ Craig D. Slater Director June 20, 1999 - ---------------------------- (Craig D. Slater) /s/ W. Thomas Stephens Director June 20, 1999 - ---------------------------- (W. Thomas Stephens)