1) Go to Start -> My Network Place ->View Network Connections;

2) Click on the Create a new connection from the Network tasks section;

3) New Connection Wizard will be started. Click on the Next button;

4) Select Set up advanced connection and click on the Next button;

5) Select Accept incoming connections and click on the Next button;

6) Skip Devices for Incoming Connections dialog and just click on the Next button;

7) Select Allow virtual private connections and click on the Next button;

8) Check user accounts that you want to be able to connect to your Windows XP computer and click on the Next button;

9) Select Internet Protocol (TCP/IP) and click on Properties button;

10) Define how you want the phones to get their IP addresses and press Ok button (example below assigns IP addresses to each client from a pre-defined pool. Make sure that allocated IP addresses are in the same address segment as your server);

11) Click Finish to complete;

12) The connection Incoming Connections is saved in the Network Connections folder.

13) If the VPN server is situated behind a router, the Port Forwarding will need to be done on the router. Standard port usage for PPTP is 1723. This port will have to be forwarded to the VPN Server IP address.

14) Use your router's IP address as a Host address for your VPN connection on a phone.