See Apple Handoff
To transfer from one function or system to another. For example, self-driving cars require a handoff from automatic to the human driver when a situation arises that it cannot figure out on its own.
Switching a cellular phone call from one radio channel to another. Also called "handover," it mostly occurs when a mobile user travels into the range of an adjacent cell. However, when there is excessive interference on a radio channel, switching can occur within the same cell.
The handoff can be managed within the base station; the base station controller (BSC) that manages several base stations; or the mobile switching center (MSC) that sets up and tears down the calls. The switch typically takes place in about a quarter second so that the caller is unaware of it.