Trying to overlay a Dialog on top of the system InCallUI. This never works reliably due to SYSTEM_ALERT_WINDOW restrictions and the fact that the system InCallUI has the highest priority ( TYPE_APPLICATION_OVERLAY is lower than TYPE_PHONE ).
The InCallUI activity requires an absurdly fast start-up time. Telecom starts a "warm-up" process pre-emptively. If your InCallActivity takes longer than ~200ms to inflate its layout or bind to InCallService , the system times out. The call connects, but the UI never appears. incallui
But here’s the catch: For a long time, InCallUI was a tightly guarded, OEM-specific application. With the introduction of the Telecom framework and ConnectionService APIs, Google attempted to standardize it. Yet, the reality remains messy. Trying to overlay a Dialog on top of the system InCallUI
Use adb shell dumpsys telecom and look for InCallController . If you see mIsBound = false while a call is active, your UI has crashed silently. Customizing InCallUI (The Right Way) Let’s say you're building a VoIP app (like WhatsApp or Signal). You don't want to replace the system dialer. You want your own call screen inside your app. Telecom starts a "warm-up" process pre-emptively