Japanese customers set to get first unlimited voice plan as NTT Docomo prepares for launch next April 2014

"NTT DoCoMo intends to launch an unlimited voice plan next fiscal year, a first for a major Japanese mobile carrier."

Source: 

DoCoMo Eyes Unlimited Voice Plan

The Nikkei

Friday June 7th,2013

http://e.nikkei.com/e/fr/freetop.aspx