Hmm, this could be a number of issues.
Do you see any network connection on the device? Are you trying to use this with T-Mobile service? Have you already checked network compatibility between your phone and our network?
I solved the issue. What I did today was to borrow a SIM from a friend of my using a T-Mobile Android. With that the phone immediately found the carrier and was allowing SIM Phone calls. I think this got my phone registered on T-Mobile. I then put in my own SIM in slot1 and everything worked fine; I go both Wi-Fi and SIM calls. When the Wi-Fi is turned off I get VoLte, when it is off I think it reverts to 4G.
I do not have data on my SIM so, when the phone looses the Wi-Fi connection, it says "no service", but that's is not true; I do have voice and text. In Slot 2 I have a European Vodaphone SIM, this also registered.
This tells me that the BLU R1 HD is compatible and that one doesn't need a new SIM to keep using T-Mobile with a new Android phone.
Thanks for your attention.