@ScarletP 5G sims are backwards compatible with 4G networks but if for example your phone is 4G only with a 5G sim installed, you wouldn't get 5G speeds because the phone wouldn't have the necessary hardware to support 5G tech. I'm guessing however your current phone is 5G compatible? but if as pointed out your 5G sim connects to a 4G network, you won't get 5G speeds. I hope that explains it and I hope I understood what your were putting across.
