Any notice or other communication under this Agreement must be in writing and shall be effective upon hand delivery; upon fax transmission to either party at the number provided below for that party, but only upon receipt by the transmitting party of a written confirmation of receipt; or three (3) business days after deposit in the U.S. mail, postage prepaid, certified or registered, and addressed to the Company at 15301 Dallas Parkway, Suite 500, Addison, Texas 75001, (Attention: Mr. Robert Michelson, President and Chief Executive Officer) or to Optionee at the address set forth on the front page hereof. Each party is obligated to notify the other in writing of any change in address. Notice of change of address shall be effective only when done in accordance with this section.