Free for Qualified Users.
Upon download, the ClearCaptions app will direct you to a page where you can enable ClearCaptions by registering for the service, and self-certifying that you are eligible to use the service. Once enabled, ClearCaptions is free to use.
There are two ways you can use ClearCaptions on your device: simultaneous voice and captions, or captions only. To see captions and hear the call at the same time, you must have a simultaneous voice and data connection, and your phone must be able to accept inbound calls. For captions only, you'll only need a data connection, and will need to use a different phone for the audio portion of your call. In either case, the data connection can be through your wireless carrier or over wifi.