If you get a phone line with your internet provider why do you get less SPEED? [View all]

Moving, going to be using Comcast because ATT speeds offered max is 50, I need more so getting Xfinity 250 Mbps down.

I MIGHT need a phone because my Verizon signal IN the house is terrible for a variety of reasons. If wifi calling works, fine, if not then I might need a phone line provided by Comcast

BUT

Each time I look at internet only on the Comcast pages I can choose up to 1000 mpbs but whenever I add a phone to it the max speed offered when I do that is 60 mbps.

Without getting into the "why do you think you need those speeds", why is this?

(I stream 4k on more than one device at a time and am willing to pay for higher speeds even if I dont need them)