HFP Blocker — keep your Bluetooth music on A2DP

What it does

When another app opens the microphone, Android often flips your Bluetooth headset from A2DP (stereo media) into Hands-Free Profile (mono 8 kHz telephony). Music collapses to a tinny phone-call timbre and takes 10–30 seconds to recover — if it recovers at all.

HFP Blocker runs a small background watcher that reverts every HFP/SCO switch back to A2DP the moment it happens, and (where possible) disconnects the Hands-Free profile from your paired headphones without affecting media.

How it works

Reflection-disconnect (preferred) — asks the system to drop the Hands-Free profile connection to your paired headsets, leaving A2DP untouched.
Mode-revert poll (fallback) — watches AudioManager.mode and reverts any switch into IN_COMMUNICATION back to NORMAL.
A persistent notification shows which strategy is active and how many HFP attempts have been blocked.

Features

One-tap toggle. Start/stop from the app or a Quick Settings tile.

Zero data collection. No account, no telemetry, no microphone access.

Works offline. Everything runs on-device; the network is only used by the AdMob banner.

Pro unlocks custom poll intervals, proactive HFP re-assert, per-app allowlists, and no ads.

Known limits

Some manufacturers gate the low-level HFP-disconnect API behind a signature permission that third-party apps can't obtain. On those devices the app falls back to audio-mode reversion, which is less reliable. The persistent notification tells you which strategy took effect.