Enabling jitter buffer

Jitter buffer is not enabled by default, but in case of network problems, it can be enabled to improve the call quality despite a n higher call latency.

To enable it you need to edit /etc/asterisk/sip.conf, adding one of more of the following commands:

jbenable = yes|no : Enables the use of a jitterbuffer on the receiving side of a SIP channel.
jbforce = yes|no : Forces the use of a jitterbuffer on the receive side of a SIP channel. 
jbmaxsize = Number : Max length of the jitterbuffer in milliseconds. 
jbimpl = fixed|adaptive: Jitterbuffer implementation, used on the receiving side of a SIP channel. Two implementations are currently available - "fixed" (with size always equals to jbmaxsize) and "adaptive" (with variable size). 

A typical activation includes:

jbenable=yes
jbforce=no
jbmaxsize=1000
jbimpl=adaptive

Once the jitter buffer has been activated in sip.conf, you need to reload the sip module using:

asterisk -rx 'sip reload'