Version 2.1, released in 2007, did not further increase data rates but nonetheless offered a handful of significant improvements to Bluetooth, including, most notably, the introduction of secure simple pairing (SSP). SSP simplifies the task of connecting two Bluetooth devices by introducing a few different connection methods.
Whereas versions 2.0 and earlier required PIN code-based device pairings, version 2.1 introduced a less work-intensive pairing method while retaining the original numerically-based pairing options as well. The primary new method introduced in version 2.1 is referred to as “just works,” which, as the title suggests, connects nearby compatible devices without requiring any user initiation.
Despite the simplification of device-to-device connectivity introduced through SSD, version 2.1 also improved device security over previous core specifications. Version 2.1 also further reduced battery consumption and introduced another new characteristic, Extended Inquiry Response (EIR), which allows the user to learn more information about the devices in range before connecting.
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