You do not need a phone line for Hyperoptic broadband.
Hyperoptic runs its own fibre cabling and therefore a phone line is not required.
You can continue to use your existing phone line or take out a broadband package from them that also includes a phone line.
Their phone service is a VOIP (Voice Over IP) service which means that the phone line uses the Hyperoptic broadband connection.
The Hyperoptic broadband router has a phone port on it which is where you will be able to plug in any standard phone.
You can keep/port your existing phone number to hyperoptic. The porting process takes approximately 15 days.