Apparament on ne peut pas, peut être je me trompe mais dans l'article c'est écrit ça :

A 56k modem in your PC will only connect to the Dreamcast at 33.6k/bps max. This is because the upload speed on a 56k modem is capped at 33.6k, and that is what you're basically doing: uploading information to the Dreamcast. This isn't as bad as it seems, though, because 56k modems rarely if ever connect at the full 56k over a phone line. The data is traveling nowhere near as far either, which means less data loss because of line noise. And if you're using broadband, the data will stream into the Dreamcast at a full 33.6k/s without the lag that is characteristic of dial-up connections. In case you're wondering, PSO works great in this setup; 33.6k is more than enough bandwidth to play online.