[Freeswitch-users] Choppy voive in conference from fritzbox to freeswitch (ptime:30 msecs)

[Peter P GMX]

Hello Michael,

I made some tests with Freeswitch and Fritzbox and found by Wireshark that:
within one call

    * Freeswitch starts sending 20msec packets, then after ~0,2 second
      sends 30msec packets
    * FritzBox always sends 30msec packets.

The average jitter is below 2 msec in both directions.
 
The below logs shows that Freeswitch considers the FritzBox to be broken
and starts using 30msec packets. But there is no SIP message from FS to
Fritzbox telling him that FB will use 30msec packets. SDP from FS to
Fritzbox always shows ptime:20

BTW: We can ship you a FritzBox if you need one for testing.

Best regards
Peter


Log:

2009-08-21 17:15:50.271555 [DEBUG] switch_rtp.c:1138 Starting timer
[soft] 160 bytes per 20ms
2009-08-21 17:15:50.281563 [INFO] mod_sofia.c:1499 Ring SDP:
v=0
o=FreeSWITCH 1250837460 1250837461 IN IP4 182.xxx.xx.xxx
s=FreeSWITCH
c=IN IP4 182.xxx.xx.xxx
t=0 0
m=audio 30290 RTP/AVP 8 101
a=rtpmap:8 PCMA/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=silenceSupp:off - - - -
a=ptime:20
a=sendrecv

2009-08-21 17:15:50.281563 [NOTICE] mod_sofia.c:1502 Pre-Answer
sofia/internal/02xxxxxxxxx at fs1.my.domain!
2009-08-21 17:15:50.281563 [DEBUG] switch_core_session.c:630 Send signal
sofia/internal/02xxxxxxxxx at fs1.my.domain [BREAK]
EXECUTE sofia/internal/02xxxxxxxxx at fs1.my.domain
playback(voicemail/8000/vm-that_was_an_invalid_ext.wav)
2009-08-21 17:15:50.281563 [DEBUG] switch_ivr_play_say.c:1097 Codec
Activated L16 at 8000hz 1 channels 20ms
2009-08-21 17:15:50.281563 [DEBUG] sofia.c:3302 Channel
sofia/internal/02xxxxxxxxx at fs1.my.domain entering state [early][183]
2009-08-21 17:15:50.281563 [DEBUG] switch_core_io.c:649
sofia/internal/02xxxxxxxxx at fs1.my.domain receive message
[TRANSCODING_NECESSARY]
2009-08-21 17:15:50.531551 [WARNING] mod_sofia.c:799 We were told to use
ptime 20 but what they meant to say was 30
This issue has so far been identified to happen on the following broken
platforms/devices:
Linksys/Sipura aka Cisco
ShoreTel
Sonus/L3
We will try to fix it but some of the devices on this list are so broken
who knows what will happen..