A client have 2 existing sonicwall devices with site to site VPN. Main site has UC540 with a dozen phones. The client want to have 2 SPA504g phones on the remote site behind the remote Sonicwall VPN. Unfortunatley SPA525s are not an option as per the customer.
Any information in this regard would be very much appreciated.
Thank you for your help. I used the #1 solution. I called Cisco support and they told me that 10.1.10.0 and 10.1.1.0 both networks need to be forwarded. Instead of that, I did 10.1.0.0. Even with the DHCP giving 150-TFTP for 10.1.1.1, the SPA504 still would not work. In the SPA504 network configuration, there is no place you can manually configure the TFTP. The SPA525 you can manually configure it.
I took the phone to the client's main office which had the PBX, configured the phone and then I brought it back to the remote office. After plugin it worked right away. I guess, as long as the phone does not get factory reset, it will keep working.
Not sure how I can manually configure the TFTP on the SPA504. The settings have a padlock and not sure how to unlock them.