As far as I can see speeds are compatible. I'd like to get away from the Verizon land-line and the ATT&T satellite dish and just use the cell phone ... if practical/possible.
Landline phones are a technology which strikes me as rapidly heading towards obsolence - I haven't had one for more than a decade. I recently saw an online contact form which put a little note that you needed to enter a landline since they couldn't call cellphones. Presumably they also only accept payment in guineas.
We don't have a landline connection in the flat any more - the previous owners removed it. Internet just comes through the TV cable. Trying to use only cellular data would cost exponentially more, but as I said I guess it all depends on market provision where you are.
Strange to think how technology infrastructure changes so quick. I'm not that old, but when I was younger only rich people had satellite or cable TV - everyone else got TV though the analogue aerial. Now we don't even have analogue tranmission - almost everyone here gets TV through cable or the telephone line; or they just don't have TVs and rely on the internet. Maybe in a few years time mobile data will be the normal way to do these things.