Denreishinki

The is an electronic inter-dimensional communications device that looks nearly identical to cellphones found in the Human World. It is used by Shinigami officers while on an assignment in the Human World.

Overview
The Denreishinki allows a Shinigami to communicate with Soul Society while in the Human World. The device also contains a system similar to a GPS tracking system for Hollow detection. Hollows located within a given area will be indicated in a mapping function of the device. It is also capable of detecting nearby Shinigami and can inform the user of whether they are geographically the closest to their target. Rukia Kuchiki used a Denreishinki on multiple occasions for communication and Hollow detection when she was assigned to Karakura Town.