OK, let me correct a couple of oversimplifications.
What you really created is technically a Use Case Scenario, meaning a specific interaction with a specific device to achieve a desired outcome given a specific initial state.
Scenarios are instances of a single use case.
I could give this scenario and my cell phone to a friend and ask her to return the call.
Assuming they followed the steps faithfully, they would probably achieve the same outcome.
However, there could be situations in which they were unable to achieve it. For instance, what would happen if they pushed the Power button on my phone and the battery was empty?
They would not even get to step 2 let alone complete the entire Scenario.
To ensure that this situation is covered, I could add a second PRE-CONDITION: The phone has sufficient power.
Adding that condition would not change the Scenario I described, it simply clarifies it by documenting a pre-condition that I didn’t think about because it didn’t happen when I executed the scenario.