unfortunately, i don't have any definitive info on SIMBA VoWIFI support.
just like on other telcos, using the same phone, some will support, some won't.
my layman understanding is that the telco makes the choice on which phones to support, and most of the telcos don't publish updated exhaustive lists. So we can only guess the causes.
same here, where i can, i enable VoWIFI and make it the preferred (over VoLTE).
when it doesn't work, i can only shrug my shoulders and send feedback, but usually there's no reply, or i get a standard "we're looking into it" and subsequent silence.
edit: my guess is that more "popular" brands will get VoWIFI, but i can't confirm it as i've sold off my last Samsung