If The user is answering the call between the 1st and 2nd ring it could be caller id data that is mistaken for fax/modem.
I looked for a similar issue recently and spent some time before answering one of my own test calls and hearing the sqeel. I Immediately recognized it and told them not...
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.