To resolve the issue of Hiya not effectively screening calls on your iPhone, follow these detailed steps:

1. Verify Hiya Permissions

Ensure that Hiya has the necessary permissions enabled in your iPhone settings:

- Open the Settings app on your iPhone.

- Scroll down and tap on Phone.

- Tap Call Blocking & Identification.

- Ensure that the switch next to Hiya is turned on. This allows Hiya to identify and block unwanted calls - learn more.

2. Restart Hiya and Your iPhone

Sometimes, a simple restart can resolve temporary glitches:

- Force-quit the Hiya app. To do this, swipe up from the bottom of the screen (or double-click the Home button) to open the app switcher, then swipe up on the Hiya app to close it.

- Restart your device by pressing and holding the Power button and sliding to power off. After it turns off, turn it back on - learn more.

3. Reinstall Hiya

If issues persist, consider reinstalling the app:

- First, uninstall Hiya by pressing and holding the app icon on your home screen until it jiggles, then tap the X to delete it.

- Restart your iPhone again after uninstalling.

- Reinstall Hiya from the App Store.

- Open the app and set it up once more, ensuring permissions are correctly granted - learn more.

4. Check for Software Updates

Ensure that your iPhone is running the latest version of iOS:

- Go to Settings > General > Software Update.

- If an update is available, download and install it to ensure compatibility with Hiya - learn more.

5. Turn Off other Call Blocking Features

Other call blocking features may conflict with Hiya:

- Go to Settings > Phone > Call Blocking & Identification and check for any other apps that may be blocking calls alongside Hiya. Temporarily disable them to see if that solves the issue - learn more.

6. Contact Hiya Support

If none of these steps resolve the issue, you might want to contact Hiya customer support:

- Visit their support page and submit a detailed description of the problem, including what troubleshooting steps you’ve already taken - learn more.

By following these steps, you should be able to restore Hiya's functionality for screening calls on your iPhone.