Help Region lock issue with S8+

[Yashraj]

Hi,
So I purchased my Galaxy S8+ plus from Italy when my iPhone brokedown.
As per the requirements mentioned in the manual, I placed a 5 minute call from my German sim card to unlock to phone for international roaming.
Now, after returning to India, when I enter my Indian SIM card, it gives me an error stating Invalid SIM inserted, and I need to provide a SIM unlock code. For some reason, my American T-mobile SIM works just fine even in India.
The model is SM-G955F.
I contacted Samsung Italy to request the code and provided them with IMEI and other details they needed, however it's been a week and they're still taking time to generate the code.
I found a lot of online unlock website too, but they ask for carrier, which I cannot provide since I bought an unlocked phone for full price.
Can someone recommend what can I do to unlock the phone ASAP?

 

[mikedt]

What Indian carrier is the SIM for? If it's MTS, which is a CDMA/EVDO network, I believe this European version phone will not work with it. https://willmyphonework.net/

The fact it works with a US T-Mobile SIM, sounds like it's not region locked and you correctly activated it for international use.

 

[Yashraj]

What Indian carrier is the SIM for? If it's MTS, which is a CDMA/EVDO network, I believe this European version phone will not work with it. https://willmyphonework.net/

The fact it works with a US T-Mobile SIM, sounds like it's not region locked and you correctly activated it for international use.

It's GSM SIM if that's what you're asking

 

[mikedt]

It's GSM SIM if that's what you're asking

If it's a GSM network SIM then it should work, especially as the American T-Mobile SIM works this European version phone. If nobody else has any ideas to try, you might have to enquire with Samsung tech support about it.