CallingMart, the company that provides wireless airtime cards at a discount is currently running the following promotions which expire on 6/23/15
Use code: dad1510 for 10% Off AT&T Refills
Use Code dad157 for 7% Tracfone and Verizon refills.
Use code: dad155 for 5% off the following refills:
Net10, PagePlus, Simple Mobile, H2O, Red Pocket & Airvoice Refills.
The codes work for such things as data add-on cards, pay as you go and monthly prepaid plans, and are only valid on purchases of $18 or more.