Challenges and Pitfalls of Creating a Telephony App
summary
Klink is a cross‑platform softphone that implements a SIP backend + WebRTC client so apps can call PSTN numbers via Asterisk/3CX while mobile clients speak WebRTC. Call audio needs explicit Android handling (AudioManager) and a proximity screen‑off wake lock and a partial wake lock (must be reacquired roughly every 5 minutes). Incoming calls use FCM but push delivery can be delayed 1–3 hours due to vendor standby buckets. Call state synchronizes via Firestore events and a FlowRedux state machine; use libphonenumber to normalize to E.164.
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chapters (11)
- 0:00Introduction
- 1:50Telephony app basics
- 3:37SIP vs WebRTC protocols
- 7:33Audio focus management
- 9:19Call stability issues
- 11:44Android telecom integration
- 16:59Incoming call handling
- 17:40Push notifications and standby buckets
- 20:29Call state management
- 25:03Phone number formats
- 26:46Summary and takeaways
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