Modem Settings

I finally ggot connected to the internet with ubuntu using an external modem I bought a Trendnet TFM-560X and it works good,except that as soon as ubuntu starts it automatically connects me to the internet.How do I get it to not connect unless I sign on?

how to install modem AT&T at Ubuntu 11.04

i wanna to install my modem device at ubuntu but i don't know how to install please give me a direction to set up my modem at ubuntu.
and for all the device like smart friend, modem three, and etc....