A. It is true that dialup modems have become almost obsolete due to broadband Internet connections, there are still situations where dialup access can prove useful :)
Under Linux you can dial out using program called wvdial. It is a PPP dialer with built-in intelligence. It dials a modem and starts PPP in order to connect to the Internet. The connection started with wvdial can be dropped by switching back to the terminal from where it was started and pressing ctrl-C.
The default configuration file is: /etc/wvdial.conf.