[h323plus] Renegotiate media port

Diego Carvalho Domingos ddomingos at daitangroup.com
Wed Apr 19 12:01:08 EDT 2017

Thanks once again Jan,

Actually my gateway does not proxy media. After reading your answer, I searched and found that CloseLogicalChannel has a parameter fromRemote. Is that what you are talking about? This would send a request channel close, right? Regards,

Diego Carvalho Domingos
System Development Specialist
+55.19 3112-1200-1286 
DaitanGroup | www.daitangroup.com | Accelerating.T
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-----Original Message-----
From: Jan Willamowius [mailto:jan at willamowius.de] 
Sent: quarta-feira, 19 de abril de 2017 12:53
To: Diego Carvalho Domingos <ddomingos at daitangroup.com>
Subject: Re: [h323plus] Renegotiate media port

The ports you receive media on affect both your sending and receiving media channels (the channel where you send media is in the same RTP session as the receiving channel and thus the RTCP ports should match).
So you would have to close sending and receiving channels and hope that the other side re-opens their sending channel.

Sending a TCS0 and doing a full re-negotiation seems like a good choice.

But as I said on the board, since your gateway proxies media, I'd try to keep the port the same during the call and eg. copy the data from the SIP side from one port to the other etc. Thats probably a lot of work, too, but better than closing and re-opening channels.


Diego Carvalho Domingos wrote:
> Thanks for answering Jan,
> I tried that but then I realized that the port that the H323 device should send media to goes in the OLCA, so closing and reopening my local OLC does not help. I'm missing something here? 
> After realizing that reopening the OLC would not help, I restarted the 
> whole negotiation by sending an empty TCS and, after receiving the TCS 
> Ack, a non-empty TCS. This in fact worked but I thought it's too 
> complex. Would reverse logical channel parameters help here? If so, 
> can you point me how to set that? I use (a subclass of) 
> H323_ExternalRTPChannel. Thanks again. Regards,
> Diego Carvalho Domingos
> -----Original Message-----
> From: h323plus [mailto:h323plus-bounces at lists.packetizer.com] On 
> Behalf Of Jan Willamowius
> Sent: quarta-feira, 19 de abril de 2017 12:10
> To: h323plus at lists.packetizer.com
> Subject: Re: [h323plus] Renegotiate media port
> Hi Tarmo,
> if you look closely, Diego is doing video.
> To my knowledge there is no free H.323-SIP gateway that supports video.
> Regarding the port negotiation:
> The only way to change the ports is to close the logical channel and 
> to open a new one. (as we discussed on the Packetizer board)
> Regards,
> Jan
> --
> Jan Willamowius, Founder of the GNU Gatekeeper Project EMail  : 
> jan at willamowius.de
> Website: https://www.gnugk.org
> Support: https://www.willamowius.com/gnugk-support.html
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> kalazeez wrote:
> > There is no need to reinvent the wheel. Use something existing and most fitting Your needs. For similar cases iI usually use Freeswitch. Just works, out of the box.
> > 
> > Tarmo
> >   
> > > On 17 Apr 2017, at 22:52, Diego Carvalho Domingos <ddomingos at daitangroup.com> wrote:
> > > 
> > > Hi all,
> > > At some point after the call has been successfully set up, I need to renegotiate the audio (it could be video as well) media port. In my case, I developed a H323-SIP gateway (that does not handle media, only signaling conversion) and the SIP side sent a reinvite with a different audio port, so I need to make the H323 device send media to this new port. How can I accomplish this? (both in terms of the H323 protocol itself and implementing the solution using H323Plus). I appreciate any help, thanks.
> > >  
> > > Diego Carvalho Domingos

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