Anyone Using Two Separate Carriers on an iPhone?

OK gang, my head-scratcher for today: I use RingCentral for business phone services but it is beginning to stink to high heaven - VOIP phone calls are missed/dropped all the time, and voice quality is a constant “can you hear me now?” battle.

What I want to do port my RingCentral business number to either Mint (for cheap) or Verizon so I can use it as my business line and continue my AT&T number for personal use, both on my iPhone Pro 13.

Anyone doing this currently? Help; thoughts; recommendations all requested.