Sprint Unlocked, but "Invalid SIM card" message.

[j2neuby]

I've been doing a lot of research the last week, but I am a novice here; thanks for your help and patience.

I have an S-ON stock M8 which both Sprint and htc have verified is listed in their systems as unlocked. I have a SIM card from a Norwegian provider called TDC, which I was previously using in my Sprint iPhone 5c here in Norway. That being said, I popped the TDC SIM over into the M8, but it says, "Invalid SIM card" and "4G services are unavailable as the SIM/UICC is invalid. Please contact customer care."

Sprint says the phone is unlocked, and provided me with an "unlock code" which I believe is the MSL code.
TDC says they don't even use any unlock codes, and told me to talk to the phone's manufacturer.
HTC said they verified it is unlocked, and when factory reset didn't fix the issue, they said it must be a Band frequency issue, where Norway doesn't support the right frequencies for my phone. But I question this, since my Sprint iPhone works here in Norway.

Any thoughts?

 

[redpoint73]

The error message says 4G is unavailable. Does anything work on the network (such as GSM voice, or 3G data)?

 

[j2neuby]

The error message says 4G is unavailable. Does anything work on the network (such as GSM voice, or 3G data)?

No, nothing worked.
It seems the answer lies in that it is a Sprint CDMA-only phone, and the rest of the world uses GSM.

Since this type of phone is customizable, I suppose it's possible to unlock it to GSM bands, but I am going to need a very thorough walkthrough on how to do all of that, I would guess.

 

[redpoint73]

No, nothing worked.
It seems the answer lies in that it is a Sprint CDMA-only phone, and the rest of the world uses GSM.

That isn't correct. The Sprint version is not "CDMA-only". The phone fully supports GSM, as well as some HSPA (3G) and some LTE frequencies. It also supports Sprint's CDMA network (in addition to other network types mentioned). You can see the band support specs of the Sprint M8 here: https://www.gsmarena.com/htc_one_(m8)_cdma-6233.php

That being the case, what the HTC rep told you is not correct. You aren't going to get an "invalid SIM" message due to improper 3G/LTE band support by your local carrier. GSM is always going to work (all carriers in the world use one or two of the same 4 bands). If the phone is SIM unlocked, you would have GSM coverage.

Also, from what I can tell, Norway uses 2100 MHZ for 3G, which the Sprint M8 supports. So you should have 3G as well (if the phone was SIM unlocked).

Usually, the phone will request the SIM unlock code, if you insert another carriers SIM (if the phone is SIM locked). So I don't know why that isn't happening in your case. It has nothing to do with whether you local carrier uses unlock codes. That would only be true if it was a phone they sold to you, which of course, it is not.

 

[jerryhou85]

Please continue your discussion in thread below:

https://forum.xda-developers.com/htc-one-m8/help/htc-one-m8-wont-boot-past-initial-t3880442