US Cellular is the fifth-largest wireless telecommunications network in the nation, serving 5 million customers. If you happen to be one of these happy customers you can refer your friends to the service and receive a $50 U.S. Cellular Promotional Card (valid for for purchases at U.S. Cellular stores and uscellular.com) for each line they set up (to a maximum of 4). Your friend will also receive the same reward! You can then top this up with further referrals, to a maximum of $550 per calendar year.