The top 4 US wireless carriers agree on something. Offering free calling for the next few weeks is a good business move while also a humanitarian one after the earthquake and tsunami in Japan. First AT&T and then Verizon offered free calling to Japan and now we also have T-Mobile and Sprint joining the cause. There are slight differences between the carriers but here is the break down for T-Mobile and Sprint:
T-Mobile is offering free long distance calls to Japan for postpaid customers from March 11th until March 31st. They still charge against your minutes for calls. On the other hand if you make the calls over Wi-Fi then the calls are free. T-Mobile is also making SMS messages to and from Japan for post paid customers free during the same time period. More details here.
Sprint on the other hand is being a bit more cryptic about it saying that they are “waiving and/or crediting” fees for wireless calls and text messages to and from Japan for customers from March 11th until April 10th. I am not sure exactly how the waiving or crediting will be done but hopefully you will not have to call in. More details here.