Thank you both for the swift replies. I tried calling CS but didn't feel like sitting on the phone for an hour so I hung up.

I just bought a Nokia 225 4G bar phone pretty cheap that I checked with the T-Mo website “Bring You Own”  IMEI STATUS CHECK and got these three messages:

*Este dispositivo es totalmente compatible con la tecnología de red de T-Mobile.

*El uso de este dispositivo no está bloqueado en nuestra red.

*Tu teléfono utiliza una tarjeta SIM física para guardar información de la cuenta móvil.

Obviously the SIM in my old Samsung is HUGE and is not going to fit into the new phone.

But I confess I’m confused by what you mean by the SIM having the IMEI.

I understand the IMEI is tied to the SIM yes, but  If I have to buy a new SIM card from T-Mo, (which I am sure I'll have to) how will my Pay As You Go continue with this new phone? Isn't the Pay As You Go plan tied to that old, huge SIM?

Thanks again for your help 😀