[asterisk-users] no audio both ways with ipv6

hw hw at gc-24.de
Thu Oct 14 20:00:22 CDT 2021

On Thu, 2021-10-14 at 21:21 +0200, Antony Stone wrote:
> On Thursday 14 October 2021 at 19:22:00, hw wrote:
> > Hi,
> > 
> > when asterisk registers with the VOIP provider via ipv6 and when
> > local phones don't work with ipv6 but only with ipv4, am I to
> > expect issues?
> Do a SIP packet capture and see what the SDP in the INVITE is telling each end 
> to expect from the other.

Hmm I could try that maybe, as a last resort.

> > I'm receiving incoming calls via the provider, asterisk correctly
> > dials the phone where the calls are suposed to go to, the phone
> > rings --- and when I pick it up, there is no audio in either direction.
> Sounds like the setup is trying to do direct media - which obviously cannot 
> work between an IPv4-only phone and an IPv6-only provider.
> Make sure Asterisk remains in the audio path and it should "almost transcode" 
> for you.

I thought about that, and I think direct media isn't being used.  It works with
ipv4, and if it was using direct media, ipv4 wouldn't work, either.  IIRC I
tried with 'aor (or endpoint?)/direct_media = no'.  Unfortunately, I can't really
make test calls to try things out.

When a call comes in and I pick up the phone, asterisk says it has learned the ipv6
address of the VOIP provider on one side and the ipv4 address on the other, and the
channels are joining a simple bridge --- whatever that means.  Is there something
that would tell me if asterisk is trying to set up direct media or remains in

> I have audio working over just such an arrangement (in my case, an IPv4-only 
> provider, and phones connected via IPv6) without problems.

I wish I could try with an ipv6 phone, but I couldn't get my Polycom VVX 1500D to
work with ipv6 at all.  It was suggested on the Polycom forum that the firmware
is too old and that I update to the latest, but the latest doesn't run on this phone
because the phone is too old.  The release before the latest is supposed to work,
but that is nowhere to be found, and I didn't get any more answers.

I tried Twinkle on my computer, but that doesn't support ipv6 at all.  There must
be something special going on with ipv6 when it comes to SIP and/or RTP.

> Antony.
> -- 
> The difference between theory and practice is that in theory there is no 
> difference, whereas in practice there is.
>                                                    Please reply to the list;
>                                                          please *don't* CC me.

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