I am experiencing this strange issue and it's been ongoing for sometime. Hoping someone can help enlighten it !!!
I am using POTS lines with FXO cards and I am experiencing this screeching sound when talking on speaker, the issue seems to happen only when I am talking on speaker and seems to get worse when I talk loud, I am experiencing this issue at all locations with POTS lines and FXO cards, I am using 7940s and 7960s phones.
Has anyone experience this issue ? I appreciate any inputs / suggestions.
thanks so much in advance !!!