IP Phones with built-in VPN client

Hi guys - has anyone actually used any IP Phone's with the built-in VPN client. I know that Avaya have these type of phones as do a few not so well know vendors. We have a client that has a few teleworkers that don't like the softphone and travel a lot. Would the Avaya 370 IP Phones work connecting to a UC520? Are there any other options? Is CISCO looking to release such a device? Any ideas would be gratefully recieved?


Comments
You could try it thru the command line
If it works it would be a 4 step process.
Copy the firmware files to flash
put in relevent tftp-server statements referencing the new firmware
assoicate the firmware with a 7975 by replacing the load statement in cli
type create-cnf files to recrate the phone config files.
Here is a link that references the above:
http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/admin/configuration/...
Good luck! If it works for you please let us know!
Ted
The Cisco Spa525G
The cisco SPA 525g has a built in VPN client. I've used it with a Cisco UC500 and it works great.
Cisco 7975G Built In VPN Client
http://www.cisco.com/en/US/docs/voice_ip_comm/cuipph/7975G_7971g-ge_7970g_7965g_7945g/8_0/english/administration/guide/7970set.html#wp1271763
I cannot figure out how to upgrade the phone to 9.0.2SR1 through my UC-540 or otherwise.
Apparently the firmware needs to be bundled into the UC540 8.x update for the phones to be updated. Attempts to update the firmware via cmterm-7975-sccp.9-0-2SR1.zip are rejected.