Halcyon
Halcyon is a free Android softphone for SIP calls through a PBX, built on PJSIP and integrated with Android Telecom.
What Halcyon is
Halcyon is a free Android softphone for SIP calls through a PBX, built on PJSIP and integrated with Android Telecom. It registers over UDP, TCP, or TLS and lets users keep multiple SIP identities active, choosing an account for each call. With server-side push configured, the registrar sends a data-only FCM message before an incoming call to wake the device. Without that setup, Halcyon relies on a foreground SIP service with a permanent TLS registration, which has the usual battery cost. Android ConnectionService handles tel: and sip: calls, including from the lock screen, and Telecom-native routing supports Bluetooth headsets and Android Auto. Listed audio codecs include Opus, G.722, AMR-WB, and G.729; video codecs are limited to the arm64-v8a build. Halcyon is self-hostable, with the PBX connecting directly to FCM and no third-party push relay in the call path. The project is pre-1.0 and in active development. Signed APK builds are available from GitHub Releases; a Play Store listing is planned for the first stable release.
Good
- Supports UDP, TCP, and TLS registration
- Multiple SIP identities can run side by side
- Supports Bluetooth headsets and Android Auto routing
- Self-hostable with direct PBX-to-FCM push
- Free to install and use pre-1.0
Watch out
- Pre-1.0 and in active development
- No iOS version
- Without server-side push, persistent registration has battery cost
- Video codecs only in arm64-v8a build
Who it suits
Halcyon suits Android users who make SIP calls through a PBX and want multiple identities or Android Telecom call handling. It may also fit users prepared to configure server-side push or accept a persistent foreground service.
Verdict
Halcyon covers core SIP calling with Android Telecom integration and configurable push calling. Its pre-1.0 status and Android-only availability are important considerations.
Plans and prices
From Halcyon's own pricing page, checked 9 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Pre-1.0 free | Free | Active pre-1.0 development · Free to install and use; pricing and licensing for 1.0 will be announced before launch. |
The facts
Each one read from Halcyon's own pages, with the date it was checked.
Where it runs
- Android requirements
- The FAQ specifies Android 8.0 (API 26) or newer on arm64-v8a, armeabi-v7a, or x86_64; video codecs are currently only compiled into the arm64-v8a build.checked 9 Oct 2026
- iOS and desktop
- The site says there is no iOS version and mentions a desktop build in the repository for testing the SIP stack on Linux.checked 9 Oct 2026
What it does
- Audio routing
- Halcyon supports Telecom-native audio routing for Bluetooth headsets and Android Auto.checked 9 Oct 2026
- Audio security
- The feature list describes SRTP encrypted media and says ZRTP support is on the roadmap.checked 9 Oct 2026
- Availability
- The site says pre-1.0 signed APK builds are available from GitHub Releases, while the Play Store listing is planned for the first stable release.checked 9 Oct 2026
- Call handling
- Its self-managed Android ConnectionService handles tel: and sip: calls and supports the lock screen.checked 9 Oct 2026
- Codecs
- Listed audio codecs are Opus, G.722, AMR-WB, and G.729; listed video codecs are VP8, VP9, and arm64 MediaCodec H.264.checked 9 Oct 2026
- Development status
- The site labels Halcyon pre-1.0 and in active development.checked 9 Oct 2026
- Multiple accounts
- Users can run several SIP identities side by side and select an account per call.checked 9 Oct 2026
- PBX and FCM setup
- Halcyon is described as self-hostable, with the user's PBX talking directly to FCM and no third-party push relay in the call path.checked 9 Oct 2026
- Product
- Halcyon is a low-latency Android softphone built on PJSIP and integrated with Android Telecom.checked 9 Oct 2026
- Push calling
- With server-side push configured, the registrar sends a data-only FCM before the INVITE to wake the device for an incoming call.checked 9 Oct 2026
- Push limitation
- Without server-side push, Halcyon falls back to a foreground SIP service that uses a permanent TLS registration and has the usual battery cost.checked 9 Oct 2026
- SIP transports
- Halcyon registers with a PBX over UDP, TCP, or TLS and advertises RFC 8599 push parameters.checked 9 Oct 2026
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