Is this safer than using my SIM when traveling?

For international calls, yes — substantially so.

There is no roaming charge, no exposure to local SIM-swap fraud, no cell-tower triangulation tying you to a specific city, and your real number is never stored in the recipient's call history unless you explicitly choose to show it.

Because the service is browser-based, there is no trace left on a borrowed device once you sign out, and you can use it from any country without buying a local SIM or handing over a passport at a kiosk.

Just remember to logout when you're done