Digium Phone Jitter Settings


I would like to pursue setting a minimum jitter buffer size on Digium D40 phones.

This would hopefully make the adaptive jitter buffer less ‘adaptive’.

I understand these parameters can be set using an XML configuration. I use DPMA so I would be interested in some way of updating the codec settings in a way that wouldn’t be cancelled out by DPMA configuration.

Many thanks.


DPMA doesn’t expose methods for overriding the jitter buffer settings of the codecs. Are you experiencing a bug? Have you discussed it with Digium’s Support department?


Hi Malcolm

Thank you for your reply. I’m not experiencing a bug in this instance. I’m trying to overcome a problem with unreliable or congested networks.

The problem is, if the network is good, the latency is low and packets are delivered with jitter of <2ms and the call is good. If the network is bad, the jitter varies throughout the call, one minute it’s 2ms the next minute it’s 10ms. It appears that the jitter buffer compensates by varying how much it buffers. And this is perfectly normal. However as a result, packets can be dropped when the buffer is reducing and there can be pauses when the buffer is increasing.

By specifying a minimum jitter buffer you are telling the phone not to drop below a certain point. The result is a more stable call at the expense of some latency.

I can see that it might be possible to make an adjustment in XML but my expertise is in DPMA.

Can I set the codec and jitter buffer information using XML then switch to DPMA configuration without overwriting the setting?

I should mention that I haven’t discussed it with Digium support as it’s quite low priority and would get the opinion of users on the forum before I pester them!

Many thanks.


Negative. The configuration methods aren’t additive.

You can always take a phone in a troublesome spot, and configure it manually using XML, specifying your own jitter buffer settings, to see if any relief can be provided.