Some Android users are unable to place outgoing calls when Hiya Spam Blocker is set as the default phone app. This affects some devices, including certain Samsung phones after a One UI update.
Immediate workaround
Temporarily switch your default phone app back to your device's built-in Phone app, make your call, then switch back to Hiya Spam Blocker if needed.
To switch to the default Phone app:
Go to your device Settings → Apps → Default apps → Phone app
Select your device's built-in Phone app (labeled Phone or Samsung Phone depending on your device)
Place your call as normal using the built-in Phone app.
Switch back to Hiya Spam Blocker:
Go to your device Settings → Apps → Default apps → Phone app
Select Hiya Spam Blocker
If the workaround doesn't help
If you're unable to make calls even after switching away from Hiya Spam Blocker, contact support from Settings → Help and Support in the app. Include your device model, Android version, and a description of the error you see (if any) — this helps the engineering team investigate and solve the issue.