I\'m working with an application which connects to Huawei 3G Modem using COM ports in php. Here is my code:
You need to determinate COM port number of your USB device via some external command called trough PHP's shell_exec().
For Windows you can try this small tool:
http://todbot.com/blog/2012/03/02/listcomports-windows-command-line-tool-for-usb-to-serial/
https://github.com/todbot/usbSearch/
After you call this tool via shell_exec(), you need to parse it's output (RegExp) and look for exact COM port number based on company/device name.