A smartphone, comprising: a display; a radar system, implemented at least partially in hardware, configured to: provide a radar field; sense reflections from an object in the radar field; analyze the reflections from the object in the radar field; and provide, based on the analysis of the reflections, radar data; one or more computer processors; and one or more computer-readable media having instructions stored thereon that, responsive to execution by the one or more computer processors, perform operations comprising: determining, based on a first subset of the radar data, an orientation of the smartphone with reference to the object; responsive to determining the orientation of the smartphone, providing an orientation-based function of the smartphone, wherein orientation-based function of the smartphone is entering a do-not-disturb mode, in particular a do-not-disturb mode in which device-initiated communications are silenced, when the smartphone is determined to be in a first orientation with reference to the object; determining, based on a second subset of the radar data, a change in the orientation of the smartphone with reference to the object, wherein the change in the orientation comprising a rotation of the smartphone within a plane that is substantially parallel to a viewing surface of the display, the rotation effective to cause the smartphone to be in a second orientation with reference to the object; and responsive to the change in orientation, modifying the orientation-based function of the smartphone, wherein modifying the orientation-based function of the smartphone is exiting the do-not-disturb mode. a display; a radar system, implemented at least partially in hardware, configured to: provide a radar field; sense reflections from an object in the radar field; analyze the reflections from the object in the radar field; and provide, based on the analysis of the reflections, radar data; provide a radar field; sense reflections from an object in the radar field; analyze the reflections from the object in the radar field; and provide, based on the analysis of the reflections, radar data; one or more computer processors; and one or more computer-readable media having instructions stored thereon that, responsive to execution by the one or more computer processors, perform operations comprising: determining, based on a first subset of the radar data, an orientation of the smartphone with reference to the object; responsive to determining the orientation of the smartphone, providing an orientation-based function of the smartphone, wherein orientation-based function of the smartphone is entering a do-not-disturb mode, in particular a do-not-disturb mode in which device-initiated communications are silenced, when the smartphone is determined to be in a first orientation with reference to the object; determining, based on a second subset of the radar data, a change in the orientation of the smartphone with reference to the object, wherein the change in the orientation comprising a rotation of the smartphone within a plane that is substantially parallel to a viewing surface of the display, the rotation effective to cause the smartphone to be in a second orientation with reference to the object; and responsive to the change in orientation, modifying the orientation-based function of the smartphone, wherein modifying the orientation-based function of the smartphone is exiting the do-not-disturb mode. determining, based on a first subset of the radar data, an orientation of the smartphone with reference to the object; responsive to determining the orientation of the smartphone, providing an orientation-based function of the smartphone, wherein orientation-based function of the smartphone is entering a do-not-disturb mode, in particular a do-not-disturb mode in which device-initiated communications are silenced, when the smartphone is determined to be in a first orientation with reference to the object; determining, based on a second subset of the radar data, a change in the orientation of the smartphone with reference to the object, wherein the change in the orientation comprising a rotation of the smartphone within a plane that is substantially parallel to a viewing surface of the display, the rotation effective to cause the smartphone to be in a second orientation with reference to the object; and responsive to the change in orientation, modifying the orientation-based function of the smartphone, wherein modifying the orientation-based function of the smartphone is exiting the do-not-disturb mode.