I can't input my 11-digit mobile phone number as the sub-line number is 10-digit on the online application screen for "Omatome Seikyu Service (combined billing method)."
回答
You can't register NTT docomo lines as sub-lines with "Omatome Seikyu Service (combined billing method)."
If you have multiple docomo lines, please apply for "Ikkatsu Seikyu Service (single billing service)."
Click "here" for applications for Ikkatsu Seikyu Service of NTT docomo.
