Receiving and making calls

I just activated my Smarty sim today and waiting for my old number to be ported.

I've found I cannot make or receive calls to mobile numbers, I've only tested on one. The number is on three network. Texts between numbers is received.

4G calling is on. My network is showing as 3 and choosing network manually does say connected to Smarty, but going back to network menu shows it as 3.

Is it because my number is being transferred over, or something else?