Unfortunately, iOS does not natively support hanging up an active call through the Shortcuts or Automation app. Apple has not exposed a "End Call" or "Hang Up" action in the Shortcuts framework, so there is no direct Shortcut action available for this.
However, there are a few approaches you can consider for call make/break testing:
1. Use the Phone app's accessibility features: If you are testing on a real device, you can use AssistiveTouch (Settings > Accessibility > Touch > AssistiveTouch) to create a custom gesture that taps the End Call button. This is manual but can be triggered quickly.
2. For automated call testing, consider using Apple's XCUITest framework via Xcode. XCUITest can interact with UI elements including the End Call button programmatically. This is the proper tool for automated iPhone call testing.
3. If you are testing in a controlled environment, you can use a second device to end the call from the other side, which you can automate via Shortcuts on that device using the "Call" action followed by a timed delay and then using the phone's hardware button.
4. Submit feedback to Apple at https://feedbackassistant.apple.com requesting a "End Call" Shortcut action — this is a commonly requested feature.
For true call automation testing on iOS, XCUITest is the most viable path.