SIP in higher education

[Yul Pyun <>]

Interesting...I'm using P0S3-06-3-00 on 7960 phones, and it works with 
proxy1_address set to our proxy's ip address.  Tried setting it to our 
proxy's fqdn and that works too.  Then tried setting it to hawaii.edu and 
that works too!

Looking at ngrep...

With the proxy*_address set to domain (e.g. hawaii.edu), indeed the phone 
looks for _sip._udp.hawaii.edu, which yields our proxy's A record, which in 
turn yields the proxy's actual ip address.  Then the phone sends a REGISTER 
to the proxy's ip address in the form of From: sip:...and 
Contact: <sip:nnnnn@ip-address:5060>

With the proxy*_address set to the ip address, the phone sends the REGISTER 
to the specified ip address, without going through the DNS lookups, in the 
form of From: sip:nnnnnn@ip-address...and Contact: 
<sip:nnnnnn@ip-address:5060>

With the registration in the form of nnnnn@domain, my initial concern was 
how the registered phone will be located when someone calls it.  But 
evidently the contact info is used for location services (in my case, CSPS 
Registry database).

For the phones regitered in the nnnnn@domain format, I like the fact that 
subsequent INVITEs use the same format.

Looking ahead...
What if you had a separate registrar, would you necessarily have a SRV 
record for it?  If not, how would the end-points resolve the domain into the 
registrar's ip address?

-Yul
----- Original Message ----- 
From: "Dennis Baron" <>
To: "Candace Holman" 
<>
Cc: 
<>
Sent: Thursday, January 27, 2005 5:44 AM
Subject: Re: [sip.edu] Re: Cisco 7960 and Avaya CCS 2.1 registration problem


> > I did try do it as you suggest, but I confirmed this doesn't work in
> > the newer firmware versions (P0S3-06-3-00, P003-07-3-00).
> > "Proxy*_address" on each line is not actually the sip proxy server
> > address, it is the domain.
>
> Exactly.  This is a typical problem of vendors using confusing names
> in their configuration schemes... at least they confuse me.  Here's
> what we have working on a Cisco 79xx - we're running 5.1.0 (shame on
> us!).
>
> domain_name : mit.edu
> image_version : "P0S3-05-1-00"
> FirmLoadID : "PC030301"
> phone_label : "617-324-8903 "
>
> line1_name : "6173248903"
> line1_authname : 
> ""
> line1_password : **********
> line1_shortname : "48903"
> line1_displayname : "MIT SIP Lab Cisco 7940"
> proxy1_address : "mit.edu"
>
> proxy_register : 1
> proxy_backup : "18.7.21.118"
> proxy_emergency : "18.7.21.118"
> outbound_proxy : 18.7.21.118
>
> So I think all the *1_* fields are associated with the SIP account
> assigned to "Line 1" - ie. "proxy1_address" is really "line1_domain" -
> confusing!  So the SIP URI for Line 1 is made up of
> line1_name@proxy1_address
>  - ie. 
> sip:
>  .  So you'd see
> something like:
>
>     From: "MIT SIP Lab Cisco 7940" 
> <sip:>
>
> I'll guess at the last three lines above - that all SIP requests are
> sent to "outbound_proxy"; with "proxy_backup" as a fallback; and
> unless "proxy_emergency" is matched in the phones dial plan.  You
> should be able to leave these blank and let the phone use DNS to
> determine where to send the requests - but I don't know if Cisco
> allows that?  You also should be able to enter a FQDN in these fields
> and use DNS to specify the list of proxy addresses - but I don't know
> if Cisco supports that either?
>
> Hope this helps.  If anybody thinks I've got this wrong speak up -
> it's been a while since I've played with a Cisco phone!
>
>   Dennis
>
> =========================================================================
>
> Dennis Baron; Information Services & Technology     
> mailto:
> Senior Strategist for Integrated Communications        
> sip:
> Massachusetts Institute of Technology; Room E19-738   tel:+1-617-252-1232
> 77 Massachusetts Avenue;  Cambridge, MA  02139-4307   fax:+1-617-253-8000
>
> =========================================================================