Before you bail on your ISP, there's actually more ground to cover - switching providers might not solve this if there's something else going on with your setup. The drops during calls specifically suggest it could be a bandwidth issue, interference, or something on your equipment side that you haven't isolated yet. Have you checked what else is running during those calls? Streaming in another room, cloud backups, or even Windows updates can tank your connection right when you need it most. Also worth checking: are you on WiFi or hardwired? If you're on WiFi, interference from neighbors' networks or other devices at home (microwaves, baby monitors, even some cordless phones) can cause exactly this pattern. Switch to ethernet if you can and see if the problem disappears. That alone solves it for a lot of remote workers.
If you're already hardwired and resets haven't helped, call your ISP back but be specific - don't just say "connection drops." Tell them you want them to check for packet loss and line stability during the exact times it happens (log those). They can pull real diagnostics then. Some ISPs have shoddy equipment they hand out; asking them to swap the modem or router for newer gear costs them nothing and sometimes fixes everything. If they won't cooperate after a couple calls, that's when you look at alternatives. But honestly, jumping ship without knowing whether it's the line or your equipment is just going to leave you frustrated again.
One more thing worth trying: set up a hotspot from your phone as a backup just for calls. It's not pretty, but if your internet tanks mid-presentation, you can keep talking instead of vanishing. Gives you breathing room while you figure out the real fix.