I use 4 dialup ISP's. Modem worked 7/21-9/6 for ALL 4 dialups. Now stopped at port b4 dialtone. Tried other ports, working phone line, re-installed driver, turned off anti-virus shields. Errors 692, 668, 619. Acer told me a software configuration issue. (3 days prior, lost sound; Acer directed me to re-install Realtek driver.) CAN ANYONE TELL ME HOW TO CONFIGURE MODEM?