What is required before using the EchoLink system?

EchoLink is a system that allows licensed amateur radio operators to communicate with each other over the internet, often bridging internet streams to local RF repeaters. Because this system ultimately keys up actual radio transmitters, it is legally required that only licensed operators use it. To enforce this rule, the EchoLink network administrators require you to register your call sign and upload proof of your amateur radio license before your account is activated. The distractors are incorrect because EchoLink software is completely free for licensed amateurs, so no purchase is required. Furthermore, while reading the manual is a good idea, there is no mandatory formal training required to use the system.