The South Korean start-up Innomdle Lab has developed a wristband called "Sgnl" that enables users to make phone calls simply by holding their index finger up to their ear. The wristband connects via Bluetooth to the smartphone and automatically detects incoming calls. When users accept the call, they hold their finger to their ear and can hear the caller thanks to the bone conduction technology integrated into the wristband. The audio signals are sent via vibrations through the finger to the skull bones near the ear. The person receiving the call can reply via the microphone in the wristband.