Not all communication devices, including some tablet computers, have an input socket suitable for 3.5mm switch jack.
A Bluetooth switch interface can be used to connect a switch to a device that has Bluetooth capability but does not have an input socket suitable for 3.5mm switch jack. The 3.5mm switch jack can be plugged into the switch interface, which uses a wireless Bluetooth connection to the communication device, enabling the switch and the communication device to work together.