[Freeswitch-users] Best practices question about SIP registration

[Michael Collins]

Lawrence,

Thanks for this explanation. It was very well written. I'm looking for a
place to codify this on the wiki so that it gets preserved... :)

-MC

On Tue, Jan 8, 2013 at 1:56 PM, Lawrence Conroy <lconroy at insensate.co.uk>wrote:

> Hi there,
>  at the risk of butting in on someone else's party ...
> Nope; your interpretations is NOT best practice.
> I have some sympathy, as the term domain is overloaded within fS.
>
> A sip address consists of a userpart and a domain part -- e.g.,
> <sip:user at sipdomain>
> The sip domain is similar to an email domain -- e.g., <mailto:
> user at maildomain>
> With email, you need to do a lookup of the MX record in DNS to find the
> FQDN of the machine that handles mail for the domain.
> With SIP (see RFC 3263), you do a lookup on the SRV record (at
> _sip._udp.<sipdomain>) to find the machine that handles SIP
> registrations/incalls for the domain. That also gives you the port on
> which that machine is listening.
> (Yup, you can also have a NAPTR record in the domain to tell you where the
> SRV record is, but many folks don't bother -- for Best Practice, you
> should, but ...)
>
> There IS a "get out" clause in the SIP specs for RFC 2543 (AKA legacy)
> support that means most SIP clients will look for the SRV and, if it can't
> be found (or there's an IP address rather than a DNS -style domain, in
> which case the SIP client won't bother hunting the SRV), the client will
> guess that the domain has a machine (i.e. it will look for an A or AAAA
> record), and also guess it's listening on 5060 (the default port).
> Email is the same (mail to fred at example.com, and strictly the sender will
> do a check for a MX and then look for an A record for example.com, and
> try there).
>
> However, relying on that default "get out" clause is definitely NOT what
> you should do for BCP.
> Using the hostname as the sip domain is a kludge -- the FQDN with A record
> usually works, but it's not what you want to do.
>
> SO ... get yourself a domain, put a D2U NAPTR at that domain, put a SRV at
> _sip._udp.<domain>, and you're done. No need for an A record at that domain
> at all.
>
> (RFC 3263 is not too hard to read, for a change -- it's certainly shorter
> than RFC 3261, and it even has an ASCII art diagram :).
>
> all the best,
>   Lawrence
>
> On 8 Jan 2013, at 21:05, Steven Schoch wrote:
>
> > On Fri, Dec 28, 2012 at 8:47 PM, Tim St. Pierre <
> > fs-list at communicatefreely.net> wrote:
> >
> >> Hi Steven,
> >>
> >> I would recommend using a proper domain name as much as possible.  For
> >> one, it looks
> >> nicer!  A SIP URI is supposed to be user at domain like an e-mail address
> >> is, and I hope that
> >> one day URI dialing will be common place, so we might as well do it
> right
> >> the first time.
> >>
> >
> > What you're saying is that "domain" should really be a fully-qualified
> host
> > name that points via DNS to the actual host on which FreeSwitch is
> running.
> > That is, the domain should be "pbx.example.com" instead of just "
> > example.com", as the last example would most likely point to a web
> server,
> > not the SIP server.  Do I have that right?
> >
> > Next, in the configuration for Polycom phones (for example), there are 2
> > fields that both have the userid.  In the example in
> > http://wiki.freeswitch.org/wiki/Polycom_configuration it has:
> >
> > reg.1.auth.userId="1000"
> >
> > and
> >
> > reg.1.address="1000 at fs.domain.local"
> >
> > How is the "address" value used?  Is that sent in the SIP registration
> > message?  If that's the case, what does Freeswitch do with it?
> >
> > --
> > Steve
> > _________________________________________________________________________
> > Professional FreeSWITCH Consulting Services:
> > consulting at freeswitch.org
> > http://www.freeswitchsolutions.com
> >
> > 
> > 
> >
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>
> _________________________________________________________________________
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> http://www.freeswitchsolutions.com
>
> 
> 
>
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-- 
Michael S Collins
Twitter: @mercutioviz
http://www.FreeSWITCH.org
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