This is all correct but I have one minor addition. They might give you a tiny credit for your old phone. The one they offered me 6 or 7 years ago was $5. So instead of a $1000 loan it's $995. I passed on that.

I was actually in this situation with Xfinity a few years back. They offered me a good deal on bundling my phone and internet but of course my phone wasn't "eligible". I made sure I wasn't locked into a contract and pulled the trigger. It turns out the plan I wanted was $10/month higher than they told me but it was still a good deal so whatever. Several months later I moved places and had to cancel internet. Xfinity's prices are horrible if you're not bundling more than one service, so I looked into canceling. The phones I get are pretty cheap so fortunately the loan was only a couple hundred dollars. It was cheaper to pay that off than spend another 18 months paying Xfinity's inflated monthly prices. Then they made it as difficult as possible within the bounds of the law to port my number to a new carrier when I did switch. I never had a problem with their service but thanks to the bad faith crap they subjected me to on my way out I'll never do business with those faggots again.