DreamPi is custom software for the Raspberry Pi mini computer that was created by Luke Benstead a.k.a Kazade. It transforms your existing high-speed internet service into a dial-up connection that can be used by your Dreamcast. While there have been other methods of doing this in the past, DreamPi is by far the easiest and cheapest method. It's also a lot more polished and streamlined than the other methods and includes a service called Dreamcast Now that allows you to see when other DreamPi users are online and what they're playing. Once you're online with DreamPi, you'll be able to play any of the currently online Dreamcast games as well as browse the web using PlanetWeb, Dreamkey, or XDP.
What you'll need:
1x Raspberry Pi (Any model with an Ethernet port) 1x Linux-Compatible USB Voice Modem (e.g. Dell NW147) 1x Line Voltage Inducer (or) 1x Telephone Line Simulator (e.g. Viking DLE-200B) 1x 4GB or Larger SD or MicroSD Card (The Raspberry Pi 1 uses a standard SD card and the Raspberry Pi 2 & 3 use MicroSD) 1x RJ-45 Ethernet Cable 1x Micro USB Cable or 5v Micro-USB Power Supply (1A or higher) 1x RJ-11 Phone Cable (2 if you're using a telephone line simulator) 1x HDMI Cable (Optional)
Line voltage inducer parts: (You can purchase a line voltage inducer from here if you don't want to build one yourself. USB modems with integrated line voltage inducers are also available.)