This is a pure PHP QRCode Encode that is written in pure PHP scripts. But there is no PHP QRCode Decode as far as I know.
PHP QRCodeEncode Test

Normally we use java to do the QRCode encode and decode. We can use PHP exec command to call an external command, like java. You can install the PHP for windows and it works for me. Otherwise, you will need the javareg.exe or vjreg.exe to register the jar file in windows system and then using asp call that jar file.
QRCode Encode/Decode Java Test

If you are interested in J2ME QRCode Encode and Decode, here comes a wonderful J2MEQRCode application. By using it, you can upload the QR image into our web server.

Download the image test package here.

Let me see how the real customer doing QRCode from their Mobile Phone.