Bluetooth® technology resides on the 2.4 GHz unlicensed Industrial, Scientific, and Medical, or ISM band. The ISM band was designed to allow products like microwaves, baby monitors, and cordless phones, to be operated without requiring the user to have a license. To be clear, unlicensed does not mean unregulated; these regulations will be discussed later in the presentation. The 2.4 GHz ISM band is crowded with several devices in a home using the same frequency band, in addition to Bluetooth, Zigbee and WiFi-enabled products. In order to allow all of these devices to operate without interference, Bluetooth utilizes a method called frequency hopping spread spectrum. As shown in the graph on this slide, the signal will hop between this range of seventy nine frequencies between 2.401 to 2.480 GHz, 1 MHz each, in order to avoid colliding with other signals. The signal is also able to recognize which frequencies may be trouble spots, and learn to avoid those spots. The hopping is carried out in a pseudo-random pattern which is known to both the transmitter and receiver.