ok go to these links and they might help you
http://www.portforward.com/alcatel/st510.htm
http://www.portforward.com/alcatel/st510v42.htm
http://www.portforward.com/alcatel/st510alt.htm
and click on what program you want to portforward for example limewire and follow the instruction for your modem

If this didnt help then there is a problem with your ISP or your computer