campbellsoup06
Vendor
ihave a small 4 phone ip office it has only one combo card ,i just installed and the customer has been complaining of a humming noise on the lines, they only have 3 Pots lines. i have done everything i can think of i changed the humm filters, took a new processor with new combo card and even tried a new ds 8 card with atm 4 daughter card , the customer even changed providers and the hum is still there , any ideas on what it could be ?