[Asterisk-Users] Restricting/Negotiating H323 Port Ranges

[Michael Manousos]

Some notes regarding asterisk-oh323:

woody+asterisk at solutionsfirst.com.au wrote:
> Our VoIP provider wants to use a restricted set of ports for H323.  All
> their current users have hardware at the customer premises which does this
> successfully for them.
> 
> We are trying to set up Asterisk to do the same (with their co-operation).
> 
> I am not familiar with the H323 terms for these connections, so bear with
> me...
> 
> The (Connect/Listen) Port is 1720 (set in (o)h323.conf)
> Tcp Range 10000-50000 (set in oh323.conf or rtp.conf)

This port range is used for call control (H.245). The ports which
are used during an active connection are determined at startup and
send to the remote endpoint.

> Udp Range 10000-50000 (set in oh323.conf or rtp.conf)

This port range is used for the interaction with the gatekeeper (RAS).
It doesn't include the ports used by RTP. These are taken from
rtp.conf.

> 
> Now my tcp dump shows this with oh323 when I try to make a call to
> number at provider:
> 
> Connect from high range port (10006) to provider 1720
> They have a few exchanges....
> 
> Then asterisk connects from port 10007 to provider:2033
> 
> My provider wants this to be port 2020 all the time, but the port number
> just keeps increasing by one.
> 
> So the next call will involve a port of 2034 at their end.

If this is their port, you can't do anything about it.

> 
> Is there somewhere in either channel to restrict this middle port range to
> just 2020?
> 
> Or is there some negotiation which asterisk/openh323 libraries don't do?
> 
> Cheers,
> Woody
> 


Regards,
Michael.