actually there are many parts of the country where dialup is still the only viable option. Then the choice is either $10 a month for dialup or $400 a month for T1. Which one would you pick?
Dialup WAS always possible on Verizon, I have an old Audiovox phone that was before a "data plan" even existed. It came with a "mobile office kit" that has a USB cable and Windows software. You have to have a dial-up account, and you can call that number with the phone. The speed was 19200 or 14400, one of the two, I don't remember now. It uses your minutes, so you get unlimited usage in the evening, and possibly if you have a friends & family plan you can get truly unlimited usage. I worked on a software project back in 2005, in a remote area and we used the phone to make a "wifi mobile hotspot" before that term was even invented. It was enough to sync our code repositories and do some emergency web searches. Back in those days you installed some software on your pc to create some fake web traffic so your ISP wouldn't drop your connection if it went idle...
So, it is possible, although probably no longer implemented in any modern phone..