[asterisk-users] Voice broken during calls (again...)

Luca Bertoncello lucabert at lucabert.de
Mon Jun 22 14:44:44 CDT 2020

Am 22.06.2020 um 21:30 schrieb Michael Maier:

> Did you check to prevent transcoding?

could you explain what do you mean and how to check it?

>> On the Gateway (Banana PI), where the Asterisk server also runs, the
>> load is about 0.50 during calls and it has a Gbps LAN.
> What's running on this device on parallel? What about other network
> traffic - not necessarily to the internet interface?

On the BananaPI? Nothing other PPP, Bind, NTP, Firewall (iptables) and

>> I can't believe, the problem is here...
> That's irrelevant. You have to ensure, that the driver doesn't have any
> problems. Reducing the queue sizes of the interface may help.

I don't understand what you mean...

> - Are you using NAT or is asterisk running on the device which runs the
> ppp-interface?

Asterisk runs on PPP interface

> - What's the modem you are using? What about the wiring between APL and
> modem? Is it done correctly? [2]

Zyxel VMG1312B30A. It works correctly and using the Internet (upload and
download) is not a problem

> - Did you configure prioritization for the up-stream regarding RTP and
> SIP? This is done with the tc tool.


> - Did you correctly configure tos? For Deutsche Telekom you may use
> tos=0xb8 (pjsip). You have to verify it with Wireshark with your traces.
> You have to set it to the same value as the packages which are received
> from their server.

I use SIP, not PJSIP... Do I have to do that, too? Which value?

> - You have to use the DNS of Deutsche Telekom which they provide during
> the ppp-login because they usually provide optimal sip servers for you
> (regarding distance). You're RTT of ping (18 ms) is pretty bad. I'm
> having here 5 ms to the primary server (Telekom provides 3). See
>     dig +noall +answer _sip._udp.tel.t-online.de SRV
> e.g. (don't know the hostname for the business infrastructure)

I have a forwarding to the DNS servers of Telekom configured in my bind,
since the Gateway has to manage the internal domains, too...

Regarding the ping time: wich line do you have? I have a DSL 50Mbps.
Maybe your times are better due to a faster line?

What is your opinion about the tests I did today with the friend and his
phone as VoIP-peer?

Luca Bertoncello
(lucabert at lucabert.de)

More information about the asterisk-users mailing list