Once again - A static IP address has got nothing to do with routing your data through one line. All it means is that the next time you turn on your modem, you will have the same IP address. Take it from somebody who has written core code in large internet infrastructure projects that this is the fact of the matter.
I'm using my GSM mobile to connect to Internet since lots of proxy servers an my LAN at day job does not allow to connect to some specific ports used at my platform/broker (Genesis) so even with ordinary GSM/GPRS mobile it is possible to day-trade my trades varies from several minutes to several hours....