[cisco-voip] Voip NAT Traversal with CCM

[Sullivan, Gary, GREENWICH, Information Services]

Have you thought about Cisco communicator / softphone
I VPN in with my laptop and then use Communicator with a usb head set 
and have no problem.


-----Original Message-----
From: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net]On Behalf Of Justin Steinberg
Sent: Wednesday, January 04, 2006 9:39 PM
To: cisco-voip at puck.nether.net
Subject: [cisco-voip] Voip NAT Traversal with CCM


I'm getting more and more requests for telecommuters who wish to have
an IP phone at their residence.  For ease of management I would prefer
to just give the remote users an IP Phone and configure the phone with
alternate TFTP to contact a public IP address of a CCM tftp server. 
Of course the CCM would have to be firewalled appropriately.

The problem is that most of these users will plug their IP phone into
a cheap dsl/cable NAT router which will lead to the problem of no way
/ one way voice. The  signalling will communicate with callmanager and
the audio with a voice gateway or another IP phone.   Thus with the
phone behind a "dumb" NAT router this solution won't work.

Is there any solution that will get the job done without requiring any
hardware on the end user side?  Any solution that requires purchasing
a 79xx phone and a VPN capable router isn't going to fly.  The
hardware costs and maintenance support required will not realize a
cost savings over a PSTN line.

I know SIP has session border controllers but I'd rather not have to
worry about what phones are running SIP and what phones running SCCP.

Are there any Session Border Controllers for SCCP or any other way to
get past this NAT issue?

I've read a little about IOS NAT Application Layer Gateways but I'm
not an expert in that area.

What are other people doing?

Thanks

Justin

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