Asterisk IAX laggy, choppy, robotic sound in IVR

Asterisk Asterisk Support
1

Asterisk: Asterisk 15.1.2
System: Ubuntu
Hardware: 4 vCPU machine with 4GB RAM
CPU Load: ~2.0
General section of IAX:

[general]
bindport=9645
authdebug=yes
bandwidth=low
jitterbuffer=yes
forcejitterbuffer=no
tos=0x18
autokill=yes
language=pl
disallow=all
allow=alaw
allow=ulaw
allow=gsm

Hello all

I have problem with playback of sound files in my IVR. I’m using IAX because my clients need to pass through NAT. I have GSM audio files mostly. When client calls 90001 Asterisk direct him to IVR menu:

extensions.conf:exten => 90001,1,Goto(IVRMainMenu,start,1)

Then first sound file is being played and from beginning it sound laggy, choppy or kind of robotic. I tried different codecs, and I’ve tried to convert that sound to alaw, ulaw, wav. Nothing improves the situation. Problem occurs on both, wifi local connection or WAN through NAT.

Some iax2 nestats:

G143*CLI> iax2 show netstats
                           -------- LOCAL ---------------------  -------- REMOTE --------------------
Channel               RTT  Jit  Del  Lost   %  Drop  OOO  Kpkts  Jit  Del  Lost   %  Drop  OOO  Kpkts FirstMsg    LastMsg
IAX2/karol-135          3    5   81     0   0     4    1      1    0    0     0   0     0    0      0 Rx:NEW      Tx:ACK
1 active IAX channel
G143*CLI> iax2 show netstats
                           -------- LOCAL ---------------------  -------- REMOTE --------------------
Channel               RTT  Jit  Del  Lost   %  Drop  OOO  Kpkts  Jit  Del  Lost   %  Drop  OOO  Kpkts FirstMsg    LastMsg
IAX2/karol-135          3    5   81     0   0     4    1      1    0    0     0   0     0    0      0 Rx:NEW      Tx:ACK
1 active IAX channel
G143*CLI> iax2 show netstats
                           -------- LOCAL ---------------------  -------- REMOTE --------------------
Channel               RTT  Jit  Del  Lost   %  Drop  OOO  Kpkts  Jit  Del  Lost   %  Drop  OOO  Kpkts FirstMsg    LastMsg
IAX2/karol-135          3    4   80     0   0     4    1      1    0    0     0   0     0    0      0 Rx:NEW      Tx:ACK
1 active IAX channel
G143*CLI> iax2 show netstats
                           -------- LOCAL ---------------------  -------- REMOTE --------------------
Channel               RTT  Jit  Del  Lost   %  Drop  OOO  Kpkts  Jit  Del  Lost   %  Drop  OOO  Kpkts FirstMsg    LastMsg
IAX2/karol-135          3    5   81     0   0     4    1      1    0    0     0   0     0    0      0 Rx:NEW      Tx:ACK
1 active IAX channel
G143*CLI> iax2 show netstats
                           -------- LOCAL ---------------------  -------- REMOTE --------------------
Channel               RTT  Jit  Del  Lost   %  Drop  OOO  Kpkts  Jit  Del  Lost   %  Drop  OOO  Kpkts FirstMsg    LastMsg
IAX2/karol-135          3    5   81     0   0     4    1      1    0    0     0   0     0    0      0 Rx:NEW      Tx:ACK
1 active IAX channel

I have no idea what could cause this. Any suggestions? Thanks in advance.

2

I’d start there, you have two processes that are CPU bound.

If you need to reduce CPU use I’d transcode your files to the native channel format of your trunk.

3

With 4 cores 2.0 load it’s should not be a problem (max for that platform is 4.0).

4

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