Hello, I'm a voip tech with 10 years of experience on the level2/NOC department working for a US company, I'm very familiar with many SIP devices, ATA, softphones and PBX systems like Asterisk/FPBX and I have built many customizations before; I read your project details, and I see you want to implement an answering machine detection, is this supposed to be some script to check voice-mails that were left and detect whether or not it has a human voice in it? Or you are talking about the MWI system that detects if there is a new voice-mail and notify the phone or client ? Feel free to contact me to discuss more about your project.
Thank you.