If you see an "A", this means that we think there is a connection on that line. I would suggest you confirm your config (either "async mode interactive" or "async mode dedicated", and with interactive you should have the "autoselect" commands under the line, and either "modem inout" or "modem callin" on the lines, too), and you should ensure that you are running recent IOS sw, at least 12.1 latest.