Real-time communication media are known as

Real-time communication media are known as synchronous media.

They require sender and audience to be present together at the same moment, as in live television or radio.

Vertical media names a direction of information flow, not timing.

Asynchronous media, such as printed matter or recordings, do not need simultaneous presence, so they are the opposite case.

Grapevine media refers to informal rumour channels, unrelated to timing.

Email and recorded video are typical asynchronous forms.