Maybe because I don't want to run for the phone, or answer calls from those trying to get money from me, I have a land line phone, have a phone in each room in the house, all with caller ID...also have caller ID on my tv from Comcast. Cell phones are great, hubby and I each have one, but I don't carry it around all the time so if I'm in the kitchen and the phone is in the bedroom....I have no idea who's calling and I have to run to get the phone....did I mention I really don't like running to answer the phone...
You don't have to have a land line phone if you don't want....try it and see how you get along. If you find you'd be happier with one, then Comcast or Century Link can provide the service for you.