[Larry Cook1]

Are there any negatives with using Wi-Fi calling if you have unlimited minutes?

[Tartarus]

I don’t think so.
WiFi Calling is just the same as ‘normal’ calling, in all regards, except for that it uses your WiFi connection instead of a cell tower to place calls.

[Lee_Bo]

Are there any negatives with using Wi-Fi calling if you have unlimited minutes?

There are a few "gotchas". Check with your provider to see what ports may need to be opened on your router. While most will say it's not necessary I've found that assuming a cheap Netgear router will support wifi calling will bite you in the end.