The display shows 'Please register the main line or the ID of Ikkatsu Seikyu Service (single billing service) written in the "お客様電話番号等" field on your bills if you are already using the single billing service for each communications company.' on the online application screen for "Omatome Seikyu Service (combined billing method)."
回答
You might have input lines other than the main line which are under "Ikkatsu Seikyu Service (single billing service)."
If you are already using the "Ikkatsu Seikyu Service," please register the main line only.
