Sideband – PTT Walkie Talkie

Turn your Android device into a high-performance offline walkie-talkie and encrypted intercom. Sideband delivers instant Push-to-Talk (PTT) voice radio and secure messaging over local Wi-Fi networks, mobile hotspots, and tactical offline mesh connections—100% free of cloud servers, cellular dependence, and internet connections. Whether you are off-grid camping, coordinating tactical field operations, navigating crowded events, managing warehouse logistics, or preparing for emergency network outages, Sideband keeps your team connected when traditional communications fail.

📡 ZERO-SERVER OFFLINE DISCOVERY
• Instant mDNS & Subnet Sweeps: Automatic discovery of local peers on standard Wi-Fi, travel routers, or Android Wi-Fi Hotspots without manual IP entry.
• Complete Air-Gapped Autonomy: Zero registration, zero phone numbers, zero emails, and zero third-party cloud servers. Your communications never touch the public internet.

🎙️ LOW-LATENCY PUSH-TO-TALK (PTT) INTERCOM
• Crystal-Clear Voice: Real-time half-duplex voice streaming utilizing raw 16 kHz 16-bit PCM transmission over low-latency UDP sockets.
• Tactile Controls: Responsive press-and-hold PTT button with haptic feedback, real-time audio amplitude waveforms, and instant speaker playback.
• Hardware Audio Routing: Seamlessly toggle between device speakerphone, earpiece, wired headsets, and Bluetooth SCO audio gear.

🔒 MILITARY-GRADE PRIVACY & KEY RATCHETING
• Ed25519 Cryptographic Identity: Every node generates a unique, persistent cryptographic keypair with 6-digit Short Authentication String (SAS) Safety Number verification to prevent man-in-the-middle attacks.
• Ephemeral 1:1 Private Chat: X25519 Elliptic-Curve Diffie-Hellman key exchange deriving symmetric ChaCha20-Poly1305 authenticated encryption for direct peer messaging.
• Multi-Peer Channels with PIN Epoch Rotation: Group channels protected by PBKDF2-derived ChaCha20-Poly1305 encryption. Channel admins can rotate channel PINs dynamically; signed rotation broadcasts increment the epoch, instantly invalidating previous epoch keys to enforce forward secrecy.

📱 MODERN ADAPTIVE DESIGN
• Native Jetpack Compose: Immersive edge-to-edge UI crafted with Material Design 3 and tactical dark styling.
• Multi-Pane Adaptive Architecture: Fluidly adapts between single-pane smartphone screens, foldables, and multi-pane tablet layouts using SupportingPaneScaffold and NavigationSuiteScaffold.
• Battery-Optimized Background Listening: Efficient foreground audio service enables continuous background intercom listening with an explicit status notification.

🏕️ BUILT FOR DEMANDING REAL-WORLD SCENARIOS
• Outdoor Adventures & Hiking: Stay in voice contact off the trail where cellular reception is unavailable.
• Emergency Preparedness & Disaster Recovery: Critical backup communications during power cuts, network congestion, or ISP outages.
• Travel & Remote Work: Create an instant ad-hoc team intercom in hotels or flights using a single portable hotspot.
• Tactical Teams & Security: Air-gapped, zero-metadata encrypted voice and data interchange without telemetry.

Privacy Guarantee: Sideband does not contain advertising, trackers, analytics SDKs, or background location polling. All data and cryptographic keys remain strictly on your physical device.

Download Sideband today and experience true off-grid voice and messaging freedom.