[Serusers] Rewriting URI in the Contact field

[Greg Fausak]

Howdy,

I have a ATA186.  I may have misunderstood the COMEDIA
reference.  Does the ATA186 poke itself through a NAT router to a SIP
server???

NAT seems to be the biggest hurdle we have.

----greg

> -----Original Message-----
> From: Maxim Sobolev [mailto:sobomax at FreeBSD.org] 
> Sent: Friday, January 10, 2003 8:58 AM
> To: Greg Fausak
> Cc: 'Jiri Kuthan'; serusers at lists.iptel.org; kapitan at portaone.com
> Subject: Re: [Serusers] Rewriting URI in the Contact field
> 
> 
> On Fri, Jan 10, 2003 at 08:27:46AM -0600, Greg Fausak wrote:
> > What is this device?  Where can I get one? What does it cost?
> 
> Cisco ata186 is two-port analog telephone adapter, i.e. it has two
> standard ports for connecting ordinary phones and one 10M ethernet
> port. It supports SIP and H323 (G711, G723 and G729 audio codecs)
> and costs some US$150.
> 
> -Maxim
> 
> > 
> > Thanks :-)
> > 
> > ---greg
> > 
> > > -----Original Message-----
> > > From: serusers-admin at lists.iptel.org 
> > > [mailto:serusers-admin at lists.iptel.org] On Behalf Of Maxim Sobolev
> > > Sent: Friday, January 10, 2003 8:15 AM
> > > To: Jiri Kuthan
> > > Cc: serusers at lists.iptel.org; kapitan at portaone.com
> > > Subject: Re: [Serusers] Rewriting URI in the Contact field
> > > 
> > > 
> > > Yes, I know - we have studied all those methods in details. Our
> > > method of choice is symmetric signalling/symmetric media 
> (aka COMEDIA)
> > > due to the following reasons:
> > > 
> > > 1. Things should work without modifying or reconfiguring existing
> > > user's infrastructure (NATs) and should be compatible with all
> > > widely-used NATs.
> > > 
> > > 2. We are bound to ata186 as UA. It is compatible with 
> this method.
> > > Support for other UAs isn't required.
> > > 
> > > 3. The calls will be terminated to Cisco GWs, while 
> COMEDIA support
> > > was recently added into Cisco IOS, so that theoretically the only
> > > thing we need is to add received/rport support into 
> proxy/registrar
> > > and update IOS at termination points.
> > > 
> > > 4. No media relay is allowed, because this will create excessive
> > > bandwith load in a single point.
> > > 
> > > 5. COMEDIA support is likely to become part of the 
> standard, so that
> > > our investments into development are protected.
> > > 
> > > -Maxim
> > > 
> > > On Fri, Jan 10, 2003 at 02:26:07PM +0100, Jiri Kuthan wrote:
> > > > There is actually a plenty of options how to traverse NATs.
> > > > Sadly, none of them works in all possible scenarios.
> > > > 
> > > > a) STUN -- some phones (kphone for linux, snom hardphones)
> > > >    have the ability to "fool" NATs to accomplish traversal
> > > >    using the STUN protocols; particularly good if you cannot
> > > >    manipulate the NAT
> > > > b) geek tweaks -- you have a configurable NAT and configurable
> > > >    phones (there are some of both of them).  you 
> configure static 
> > > >    port forwarding in the NAT and phones to advertise the
> > > >    public address in contacts and elsewhere
> > > > c) ALG -- use a SIP-aware NAT such as PIX or Intertex
> > > > d) UPnP -- takes UPnP enables phones (snom is) and NATs
> > > > e) SIP/media relay -- that's a too ugly story
> > > > 
> > > > What to choose best depends on your network setting -- can you
> > > > tweak the NAT, can you afford replacing it with a SIP-enabled
> > > > one, are the phones you are using configurable or do they use
> > > > STUN, do you have a server on the public or private NAT side
> > > > or on each of them, etc.
> > > > 
> > > > I remember someone shared with us he was using ser in his
> > > > network to do the translation of SIP addresses on behalf
> > > > ot the phones. The ser script was configured to statically
> > > > rewrite private IP addresses to the public address using
> > > > replace/textops.
> > > > 
> > > > -Jiri
> > > > 
> > > > At 01:32 PM 1/10/2003, Maxim Sobolev wrote:
> > > > >Folks,
> > > > >
> > > > >I need an advise on how to better implement one feature, 
> > > which isn't
> > > > >currently present in SER. We need to allow UAs behind 
> NAT properly
> > > > >register with the registrar - by "properly" I mean that 
> > > host:port portion
> > > > >of URI in Contact field should not be used, but host:port 
> > > the request
> > > > >came from should be used instead. By definition we know 
> > > that those UAs
> > > > >will support symmetric SIP signalling, so that this scheme 
> > > will work just
> > > > >fine.
> > > > >
> > > > >In my opinion there are two ways to do it: either add new 
> > > rewritecontact*
> > > > >family of functions similar to rewritehost ones. or add a 
> > > new flag for
> > > > >the save() function. This is where I need your help - 
> > > which implementation
> > > > >looks better for you (or maybe you have even some better 
> > > idea), since
> > > > >we are really interested in inclusion of our changes into 
> > > the mainline to
> > > > >reduce our local hacks.
> > > > >
> > > > >Regards,
> > > > >
> > > > >Maxim
> > > > >
> > > > >_______________________________________________
> > > > >Serusers mailing list
> > > > >serusers at lists.iptel.org
> > > > >http://lists.iptel.org/mailman/listinfo/serusers 
> > > > 
> > > > --
> > > > Jiri Kuthan            http://iptel.org/~jiri/ 
> > > _______________________________________________
> > > Serusers mailing list
> > > serusers at lists.iptel.org
> > > http://lists.iptel.org/mailman/listinfo/serusers
> > > 
>