I don't know the number for the registration on the online application screen for" Omatome Seikyu Service (combined billing method)" or "Web Billing."
回答
After selecting the communications company in the field of phone number on the online application screen, point a cursor at the number inputting field and the details pops up on the screen for reference.
If there's no bill or "開通のお知らせ (notification of starting)" and you don't know the billing number, please contact each communications company.
