EXHIBIT 24 JOINT FILING AGREEMENT AND POWER OF ATTORNEYJoint Filing Agreement and Power of Attorney • February 27th, 2008 • Highland Capital Management Lp • Radiotelephone communications
Pursuant to and in accordance with the Securities Exchange Act of 1934, as amended, and the rules and regulations thereunder, each party hereto hereby agrees to the joint filing, on behalf of each of them, of any filing required by such party under Section 13 or Section 16 of the Exchange Act or any rule or regulation thereunder (including any amendment, supplement, and/or exhibit thereto) with the Securities and Exchange Commission (and, if such security is registered on a national securities exchange, also with the exchange), and further agrees to the filing, furnishing, and/or incorporation by reference of this Joint Filing Agreement and Power of Attorney as an exhibit thereto. This Joint Filing Agreement and Power of Attorney shall remain in full force and effect until revoked by any party hereto in a signed writing provided to each other party hereto, and then only with respect to such revoking party.
