What is the difference between Can 2 Can and the Party Line subscription?

The Can 2 Can plan provides free calling to other Tin Cans (and 911) and is included with every device, no subscription required. The Party Line Subscription ($9.99/month or $99/annually) lets your kid call approved external numbers (e.g. grandma, friends, your own cell, and more). As always, only callers you approve can communicate with your Tin Can.