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Help Phone From eBay is Unlocked?

Kim Harman

Lurker
Sep 1, 2021
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I bought a phone advertised as unlocked from eBay a couple years ago. I bought it to use on Cricket (ATT network) and everything has been running fine for a couple of years. Now, I want to switch to Xfinity (on Verizon network) and bought the SIM. I insert the SIM and it doesn't register onto the Xfinity network.

What do you think? What are some steps I should possibly take?

Regards,
KH
 
I bought a phone advertised as unlocked from eBay a couple years ago. I bought it to use on Cricket (ATT network) and everything has been running fine for a couple of years. Now, I want to switch to Xfinity (on Verizon network) and bought the SIM. I insert the SIM and it doesn't register onto the Xfinity network.

What do you think? What are some steps I should possibly take?

Regards,
KH

That's because your phone is a GSM phone, and Verizon is CDMA, so I assume Xfinity is also the same since it uses the Verizon bands.

Check your compatibility with your device, click on the Xfinty link to see, enter your IEMI number and it'll tell if your Samsung is compatible, yours might be a dual band, https://www.xfinity.com/mobile/byod/compatibility/imei

That is my best guess, might only be certain phones allowed on the Xfinity service
 
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Aren't "CDMA" carriers hybrids these days: CDMA-based 3G but GSM-based 4G (LTE), which is why they now have SIM cards. But not being American (and CDMA being largely restricted to North America) I don't have experience of how that works in practice. We also don't know for sure what model S8+ this is, since we're not told which carrier it was originally sold on, just that it was used with ATT. But while the latest Galaxy S handsets should be fully cross-compatible one of this age may not be. For example if it wasn't a 955P (Sprint) or 955V (Verizon) it won't be compatible with the 3G bands used by a Verizon-using VMO, but may have 4G compatibility depending on what bands Xfinity/Verizon use in that area. In any case it would be worth checking the compatibility of the particular model.

The other thing I don't know is whether Xfinity require some sort of handset registration? It isn't technically necessary when the subscriber ID is handled by the SIM rather than an IMEI/MEID, but since CDMA users used to have to register their handset I can't rule out Xfinity still requiring this and only allowing handsets whose ID's have been registered with them. I'm not saying that is the case - my understanding is that VZW don't do this, for example - just that it would be worth checking that they don't put any silly barrier like that in the way (silly since that would cost them money to do something that's not necessary any more).

It's a long time since I handled a locked handset(*), but I thought they usually put a message on the screen if they were incompatible due to a SIM lock. Can't guarantee that a US carrier handset would behave that way though, as I've no experience with them.

(*) Here in the UK handset locking is finally being outlawed and no new locked handsets should be sold after the end of this year. A number of our carriers dropped it years ago, and our biggest independent phone seller has only ever sold unlocked phones even on carrier contract, so it's always been easy to avoid, but I'll be glad to see the back of it anyway.
 
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I bought a phone advertised as unlocked from eBay a couple years ago. I bought it to use on Cricket (ATT network) and everything has been running fine for a couple of years. Now, I want to switch to Xfinity (on Verizon network) and bought the SIM. I insert the SIM and it doesn't register onto the Xfinity network.

What do you think? What are some steps I should possibly take?

Regards,
KH
Which model is it, exactly?
 
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You really need to try what @DonB suggested, verify that phone is compatible with the Xfinity phone service. Different carriers rely upon different types of cellular networks, and not every phone is going to be compatible with every carrier. A SIM card just retains your user account data, it's an identifier. But there are hardware and software aspects in each phone model that determine what cellular networks the phone can connect with. So SIM card is what authenticates you to use their cellular service, the phone is the what does the actual connections.
 
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Aren't "CDMA" carriers hybrids these days: CDMA-based 3G but GSM-based 4G (LTE), which is why they now have SIM cards. But not being American (and CDMA being largely restricted to North America) I don't have experience of how that works in practice.
CDMA is basically done in the US. The Sprint network is gone and Verizon has allowed non CDMA phones for several years, with their CDMA network ending next year.

Now a phone must support VoLTE on the network you want to use, but similar issues occur with that. For example some carrier branded phones wont work on another network even though the unlocked version will.

Some MVNOs will also restrict which phones you can bring, and it appears Xfinity is one of them. Their BYOD page only has options to check Galaxy, Pixel, and iPhones even though many other phones are compatible with Verizon.
 
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