I need to join YOUR cell carrier!
Mine (T-Mobile) only offers free to new customers or requires old customers to move off their current plan. I stick with my current plan (2015 vintage) because I'm not interested in paying more for my service just to get a free device.
I don't use the major carriers and pre-paid doesn't offer such deals. I absolutely LOATHE cell carriers, so I give them as little as humanly possible per-month and still have usable service. Back in the 3g and 4/4s days, I was paying AT&T well over $100/month for just my line... now I'm paying $17.50 for my line, and my wife is on a free year promo from Spectrum.
When it's time for a phone, we just buy them outright.
Edit: I also have a work-issued iPhone, so I guess I could just use it full-time and pay zero..but then MDM. 🤔