You can wait until the 1st day of next month for the data amount to renew itself, or you can unlock the voice call limit by paying an additional recharge.
To unlock the "Voice Call Limit Service", please follow these instructions:
- Log in to "My Page" https://user.jpmob.jp/users/sign_in
- Select "Recharge" from the menu
- Apply for "Recharge Voice Call Usage: 2,200 Yen"
- Check the payment due date from the "Payment" menu
- Make the additional payment
The voice call function will be unlocked for your account right after you finish your additional payment.