Tell all your VPN phones to use the IP Office's IP address as their "File Svr" (aka TFTP Server). In the IP Office, using Manager, under the System tree point the "TFTP Server" to the IP Address of any machine you like running TFTP. Or better yet go out and get yourself a $15 Compact Flash card and shove it in the slot on the back of the IP Office and put all your .bin/.txt/.scr files on that and in Manager point the TFTP Server to the IP Office itself eliminating the need for an external server altogether.
Kyle Holladay
ACA-I, ACA Call Center, ACS-I, ACS-M, TIA-CTP, MCP/MCTS Exchange 2007
ACE Implement: IP Office
"Thinking is the hardest work there is, which is the probable reason why so few engage in it." - Henry Ford