In technology teams, these interfaces are usually APIs and good documentation. When the Programmable Voice team needs to place a call to a telephone somewhere in the world, they make an API request to the Voice Connectivity layer to initiate the phone call. This well-defined service contract between teams provides a stable, predictable, and documented way for teams to interact with each other, and even accounts for billing of the underlying services. But this practice isn’t limited to just technology teams.
