Blink vs Halcyon

Blink is a real-time communications client that uses SIP to connect with service providers, Bonjour on a local network and SIP2SIP. A SIP account from a provider is required. Voice and video features include Opus audio, H.264, VP8 and VP9 video, acoustic echo cancellation and ZRTP media encryption. Messaging supports MSRP chat, OTR encryption, SIMPLE presence and XCAP server storage. File transfers use MSRP and TLS and include progress reports and delivery confirmation. Screen sharing can run with audio, while conferences can combine participant management, VoIP, messaging, presence, file transfers and screen sharing. Blink supports multiple SIP accounts, iCloud syncing between computers and built-in account sign-up through SIP2SIP. It also lists OpenPGP messaging support and says it does not collect end-user data. The free plan is free and lists Linux, Mac and Windows downloads. Available features may differ by operating system and version, and some conferencing functions require a conference server. Blink was founded in 2002.

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.