I'm experiencing problems with my 56k dialup modem?

i try to connect and it dials and makes all the noise then at the end instead or verfying user and authenticating it makes a constant hum kind of sound then error no answer comes up.I've tried pulling it out and putting it into different com ports and uninstalling and reinstalling, but still the same, also recreated new connection.What to do, was fine one minute then crap the next.