To telnet into the Speedstream 5200 E242 you need to set a username and password with ICGABE's SpeedStream 5200 FTP program (The WinPcap library is required for this to work)
Open MS-DOS or Command Prompt, type "ipconfig /all", and write down the Physical Address.
Run the SpeedStream 5200 FTP program and fill in the required info. *Note that the Interface MAC is the Physical Address you wrote down earlier.
Finally, telnet to 192.168.2.1 with the login / password you set and enjoy!