[Google Pixel 4 XL Questions & Answers] i5lee8bit:
Hi everyone. After a big blowout I had with AT&T leading me to finally leave them after our family being customers for 20 years, it led me to porting out all 5 of my family's numbers to Xfinity Mobile. Good riddance.

I'm happy to report that, unlike with AT&T, advanced calling features work with the Google Store / Unlocked Pixel 4 XL (and regular Pixel 4, which my wife is now using). VoLTE and WiFi calling both work perfectly. Both phones were immediately bootloader unlocked and heavily modified as soon as I got them. Like usual, none of the advanced calling features worked while on AT&T (for our last 2-3 days with them before I got the Xfinity Mobile SIM cards in the mail and peaced out, lol). I was worried that advanced calling might not work on Xfinity Mobile either unless you bought the phone from them, and considering they're closely related to Verizon, I wasn't sure if I would ever be able to unlock the bootloader if purchased from them. Well, you don't need to worry if you buy the factory unlocked variant.

They also extended their BYOD promo, so doing BYOD and porting out your number from your carrier will get you a $50 "rebate" so to speak per number ported out ($250 for me, wooo! My brother and parents all had iPhones that were also BYOD'd). I'll be honest, I friggin hate Comcast as a cable company, but seeing as how they're my only option for ISP for the foreseeable future, why the hell not reduce my cell phone bill by ~60-70% and be on a better network than AT&T's crap?

Oh, and also, for the last month of service with AT&T, knowing it wouldn't be a full month of service, I dropped our 35GB family plan to 3GB, expecting to save a few bucks. According to them, the total month cost was supposed to go down by ~$40. Instead, it went UP by $10. Yup, I dropped our data allotment by 90%, and our bill went UP. They didn't tell us that instead of $15 per line access charge we've been paying for years, it would become $20, and charge the primary line $45 access fee, just because. Goodbye you f"king scam artists.

PS: I'm not a Comcast shill. This is more of a PSA, and if I could convince anyone else to leave AT&T and stop giving them your hard earned money, this is all worth it.

edit for more info/thoughts: Part of the BYOD process involved entering the device IMEI numbers, before being able to order the sim cards - I suspect to check that, A) they're compatible BYOD devices, B) whether it corresponds to certain carriers, and C) for iPhones, that they are indeed carrier unlocked. I would also suspect that this process registers these devices' IMEI numbers into their database to allow VoLTE and WiFi Calling on their network. So I really don't see any reason they would suddenly pull these features away for eligible BYOD devices, done the right way. I did notice when I tried to drop the new SIM into my wife's old HTC U11, data and advanced calling wouldn't work. Like some MVNO's, this may make switching phones a little more annoying in the future, but probably easily taken care of as long as you use a compatible phone and a quick call. Ultimately still well worth it if you ask me. Oh, and my brother, mom, and stepdad use iPhone 6s, 7, and 7 Plus - advanced calling features worked on them too. 2 of them were unlocked AT&T phones, and the other was Verizon (which at the time were all SIM unlocked).