Halcyon vs MicroSIP

Halcyon is a free, pre-1.0 Android softphone built on PJSIP and integrated with Android Telecom. It registers with a PBX over UDP, TCP, or TLS, advertises RFC 8599 push parameters, and supports several SIP identities with an account selected for each call. When server-side push is configured, the registrar sends a data-only FCM message before an incoming INVITE to wake the device. Without push, Halcyon uses a foreground SIP service with permanent TLS registration and the associated battery cost. Its Android ConnectionService handles tel: and sip: calls, including from the lock screen, while Telecom-native routing supports Bluetooth headsets and Android Auto. Listed audio codecs are Opus, G.722, AMR-WB, and G.729; video codecs include VP8, VP9, and arm64 MediaCodec H.264. Media uses SRTP encryption, with ZRTP on the roadmap. Android 8.0 or newer is required; signed APKs are available from GitHub Releases.

MicroSIP is a free Windows desktop softphone for business communication and professional VoIP use. It makes voice and video calls through SIP providers or PBX systems, and can also call an IP address or domain name directly. Call Manager handles multiple simultaneous calls, conferences, blind and attended transfers, and instant messaging. Listed video codecs include H.264, H.263+, VP8, and VP9; DTMF options include in-band, RFC2833, and SIP INFO. SIP signaling can use TLS, while media protection options include SRTP and DTLS-SRTP. MicroSIP says it does not provide user accounts, phone numbers, or telephony services and has no access to end-user information. Windows is listed as supported; Linux, macOS, and BSD are listed for use via Wine. Android, iPhone, and iPad are not supported. The standard edition lists video support, while Lite does not. The project uses the GNU GPL v2 license. A custom-branded softphone build costs €150, paid once; future updates, modifications, or additional features are billed separately.