Caller ID for CGI Script

We use a Web based ordering system. Currently we have to enter customer's phone number each time a tele order is received. To improve efficiency, we need to add a Caller ID software so that Caller ID (customer's telephone number) can be captured and send to the order script automatically. You are required to write a simple program to obtain caller's telephone number and post it to a CGI script. We use PCs with Windows XP. The PCs are connected to the Internet via ADSL. We plan to use USB modem to connect to our telephone line. Please do not hesitate to contract me should you have any question.