I tried to look for a Configuration guide for Cisco phone 7941, Im trying to test the phone from outside the LAN (from Home). How will the Phone know where is the concentrator and to go to it? what do i have to configure on the Phone and Concentrator side for them to build a VPN Tunnel and start communicating?
by default, IP Phones try to get this info from DHCP, if DHCP is not an option, then you can configure a static IP on the Phone.
Also, the phone is not capable of building a VPN Tunnel, the Concentrator should be handling this and there is nothing that can be done on the phone to create a connection. The Phone would try to reach the TFTP Server using the the configuration (If Static) or Option 150 that it would have received from the DHCP Server incase available. Please check the following link for more information about how to configure a 7941 IP Phone
Hope this helps