Hi @Anonymous User
NowTV use the BT Openreach telephone line to deliver the internet at your home.
So if you are looking at NowTV Broadband you will need a telephone line installed.
From my understanding any new telephone line is included in the NowTV Broadband package price (Perhaps a previous Virgin customer on the forum who switched to NowTV Broadband can confirm ?).
Some further information in this linked guide below on switching to NowTV Broadband.