Will an Unlocked Galaxy S21 Ultra 5G work on Xfinity

I can report mine is working now w/ current SIM from old phone on new S21 Ultra Unlocked purchased from Samsung.

Question, only indicates LTE and not 5G, do I need to obtain a new SIM to enable 5G or will the old/current SIM work w/ 5G?

Thanks

I just came home and inserted sim, I'm live, 5g signal, getting update, downloading now.  Hooray!

Is anyone who got their old sim working doing the trade in offer with Samsung?

Our IMEI's will still show as our old device and not the S21, so I'm worried that someone will get the refurbished phone, try to activate it, and run into a problem. Any ideas if that would cause a problem on Xfinity's side?

My Samsung purchased S21 Unlocked is partially working, indicates unrecongnizable device and not all features are working i,.e, VM, text, and no 5G, just LTE.

Went to xfinity store and they were on no help/useless, just indicated phone is uncompatiable. At this point I don't know what to do, what a mess!

Well here is the official reply from the Manager at my xfinity wireless store:

"I know this is confusing, this work kind of like this: Your current device Samsung S21 has been designed to work in the channel number 10024, this channel may be the same than many other providers but Xfinity Mobile devices work on channel 360081 so then, that is why your device is not compatible even though it is the same model that we sell.

Being unlocked doesn`t mean that will work with all the carriers."

Going to see if I can send this back to Samsung, as according to xfinity, this phone will not work, again what a mess!

I just checked mine again, S21 Ultra Unlocked and still indictates incompatiable, head scratcher.

I have been following this since topic since Wednesday when I received my device.  I just entered the IMEI for my s21 purchased from Samsung and it is showing compatible now on XM compatibility checker.

So I believe this is the answer for anyone like me who switched to XM when they first started and weren't allowing BYOD. I had grabbed the lowest price phone and just took the sim out and transferred to my good unlocked phone. For some reason this time it wasn't just transferring service anymore(maybe too many different devices? I started with Note8, went to S10+, then to Note10+ and now the S21U) so I dug out the old Moto E5 they gave me and put the sim in it for about 20 minutes. Once it was set up and able to make calls/text I switched the sim back to my S21U and I'm getting full 5G and can finally make calls. Hope this helps some of you. 

I only have the base model.  I did have to call support because I the site would not allow me to keep my same number.  But all is good now.

I switched my Sim from my old phone to newly bought S21 Ultra unlocked phone from Samsung today moring and it is working fine. It wasn't working when I had checked yesterday. 

I also see that the compatability page says its compatible when I enter IMEI of my latest phone.