The Control Panel accessed from the Rack Rentals page has a Device Management tab that shows the Collaboration rack's logical topology. From here, you can telnet to any of the physical rack devices without needing a telnet client.
Click on one of the two routers or the switch on the topology and select Open Telnet.
A telnet session will open in an embedded frame of the main Control Panel page. You will need to hit the enter key a few times to get to the command prompt since this connects to the console port of these devices.
You have the option to move the session to a new browser window so that you can have multiple telnet sessions open at the same time. After opening the telnet session, click on the Window button and a new window will pop-up with the session.
Remember that you can have only one active telnet connection to any single device open at a time because you are connecting to the console of that device. This means that you cannot be connected to the device using a telnet client and with the control panel to the same device simultaneously. Although the method is different, they are both accessing the console, which is a single session serial line.