Systems (like CCN) and modems assume you can run faster than you really can, so when you log into CCN, CCN will 'ask' your modem if it can run at 1200 bps. Your 14,400 bps modem 'answers' yes. CCN then 'asks' your modem if it can run at 9600 bps and of course your 14,400 bps modem 'answers' yes. CCN then 'asks' if your modem can run at 19,200 bps (which is the next proper level for communications) and your modem 'answers' that it can't reach that level but it can do a 'compressed 9600' which translates into 14,400 bps (halfway between 9600 and 19200). This is what is going on when you hear the different pitch squeals coming from CCN and your modem when you dial-in. Each pitch is CCN asking if your modem can handle the higher transfer rate. Your modem sends back an identical pitch to let CCN know how high it can go.