" I want to install 6 internal 56K modems (attached to 6 phone lines) on my PC and configure them in such a way that the 1st line connects to the internet 3h/day and disconnects automatically then the 2nd line connects for another 3h/day and disconnects, and so on for the 4 remaining lines "

Just so you know... I've never seen more than ONE PCI WINMODEM at a time function in a PC. Only "HARDWARE" modems seem to work.

However, any 1st year electronics guru can solve your issue. Hint: Relays and the parallel port... Only one modem...