Hello Linphone Support Team,
We are testing Linphone for our own internal SIP softphone use with a FusionPBX/FreeSWITCH server. We are experiencing an audio quality issue mainly with voicemail and server generated audio. The issue happens both in the official Linphone Android app and in our own Android app built using the Linphone SDK. Using the same SIP account on the same FusionPBX/FreeSWITCH server, Zoiper and desk phones play the voicemail audio cleanly, but the official Linphone app and our Linphone SDK-based app both experience shaky, stuttering, or cutting voicemail audio. What we observed: - Server: FusionPBX / FreeSWITCH - Client: Official Linphone Android app and our Android app using Linphone SDK - Codec during voicemail: PCMU / G.711 - Packet loss in Wireshark: 0% - RTP timing: uneven packet spacing with large gaps - Max inter-packet delta observed: around 500 ms - Expected PCMU packet rate: around 50 packets/sec for 20 ms ptime - Observed packet rate was much lower during the problematic voicemail stream - Increasing the Linphone jitter buffer up to around 800 ms did not fully fix the voicemail stutter This makes us think the FreeSWITCH server may be producing uneven or starved RTP during voicemail playback, but we are trying to understand why Linphone exposes the issue more severely than Zoiper or desk phones. Questions: 1. Does Linphone Android or Linphone SDK have packet-loss concealment or audio gap concealment settings that can be tuned for PCMU/G.711? 2. Are there recommended jitter buffer, RTP, or audio stream settings for handling bursty or starved RTP from FreeSWITCH? 3. Are there Linphone SDK settings related to adaptive jitter buffer, PLC, RTP timing, audio playback buffering, or media stream recovery that we should test? 4. What Linphone logs would be most useful for diagnosing RTP/audio playback behavior during voicemail? 5. Are there known compatibility considerations between Linphone and FreeSWITCH voicemail or server-generated media? Thank you, Omid Farahmand TechTeam-NetLayers Inc. 📞 +1 (888) 208-8282 ✉ [email protected] 🌐 <http://www.netlayers.ca/> www.netlayers.ca 212-7163 Yonge St., Thornhill, ON L3T 0C6
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