The difference comes down to whether your iPhone is locked. A locked iPhone displays a “slide to answer” control for incoming calls, while an unlocked one offers separate options to answer or decline. The buttons may appear in a banner or across the full screen, depending on the Incoming Calls setting, but the options remain available when the phone is unlocked.
You can still manage a call without an on-screen decline button. Pressing the side button twice quickly rejects the call and sends it to voicemail. Pressing either volume button silences the ringtone without rejecting the call. Both actions work whether the screen is locked or unlocked.
To decline a call while explaining why, use the Message option on the incoming-call screen. If the call appears as a banner, tap it to reveal the available controls, then choose Message. You can send one of the suggested replies or select Custom to write your own.
Suggested replies can be edited in advance under Settings > Apps > Phone > Respond with Text. Select a reply and change its wording to suit your needs.
To block a number, find it in Recents, tap the number or its Info button in Classic view, scroll down, choose Block Caller and confirm. For unknown callers, Settings > Apps > Phone > Screen Unknown Callers offers Never, Ask Reason for Calling or Silence on iOS 26 and later. Silence sends unknown calls directly to voicemail without ringing, while Ask Reason for Calling lets callers identify themselves first.
Sources: Engadget.