From the www.bestfares.com website:

AT&T began a complimentary in-flight phone special for passengers on Alaska, American, Canadian, Northwest and Southwest airlines. You can receive a free 5 minute call by dialing toll free *3733 from AT&T in-flight phones and answering a couple of travel-related questions. You will also be asked to provide a calling or credit card number. AT&T will credit five minutes to the card at no charge, but if the call exceeds the time allowed, you are charged the regular per-minute rate beginning with the sixth minute. International calls are excluded, and voice and data calls are at regular rates.

For more information, call 800-888-7600 or go online at www.attws.com.