Claiming $200/month for a phone makes one wonder which numbers are valid. I'm not saying everyone needs to make a $100 phone last 5 years and use a $15/month plan, but I'm not even sure how I would get to $200/month in phone bill, even including financing an iPhone 17 Pro Max.
With $85/month service (AT&T unlimited premium with only a single line) and financing a $2,000 phone (The smaller storage version of the Galaxy Z Fold 7 at MSRP) over 18 months, you’d hit almost exactly that; you could so the same with a cheaper service and/or phone with some add-ons (e.g., while Apple Care is billed directly by Apple and so wouldn't be on a phone bill, insurance for non-Apple phones is often billed by carriers on phone bills.)
$200 doesn't seem that crazy if they are buying several phone lines. I assume he pays at the least his wife as well, so that's two. If they have home internet bundled in as well, that would easily explain that figure. All to say, AT&T. He may also have a home phone line for a fax machine. It is perhaps a bit disingenuous to bundle it all together, but it also isn't the main point of the article.
I pay that at least much for my family, hence why I used it
$200 seems valid - it comes from the linked article [0] and it includes home internet (I pay $110 / month Comcast just for home internet in Bellevue. In Seattle I paid $130 / month). Maybe Aaron could have phrased it better. (I also recommend to read the linked article as it is a phenomenally well done financial analysis.)
[0] https://www.yesigiveafig.com/p/part-1-my-life-is-a-lie