CNET'S QUICK GUIDE: Bluetooth headset quick guide

Features and profiles

Bluetooth comes in different versions, so make sure that your two chosen devices will work with each other. All of the newer versions are backward-compatible however, so as long as you're using the more basic Bluetooth features, you won't have much to worry about. Most products currently work on Bluetooth version 1.1, which offers such basic features as voice dialing, call mute, and last-number redial. In 2003, the Bluetooth Special Interest Group (SIG), a body that oversees the technology's development, released version 1.2 and rolled out version 2.0 a year later. Bluetooth 1.2 introduced new features to eliminate radio frequency interference through frequency hopping and added greater security to protect against snooping and tracking. Bluetooth 2.0 brought higher connection speeds (as much as three times faster in some cases), improved performance, and less power consumption. The SIG recently introduced version 2.1, which aims to improve pairing without the need for a PIN, requires even lower power consumption, and offers more security. Check out the various profiles and their features in the below chart.

Specifications	Bluetooth 1.1	Bluetooth 1.2	Bluetooth 2.0	Bluetooth 2.1 plus EDR (Enhanced Data Rate)
Voice dialing	Yes	Yes	Yes	Yes
Call mute	Yes	Yes	Yes	Yes
Last-number redial	Yes	Yes	Yes	Yes
Improved resistance to radio frequency interference		Yes	Yes	Yes
10-meter range	Yes	Yes	Yes	Yes
100-meter range			Yes	Yes
Fast transmission speeds			Yes	Yes
Lower power consumption			Yes	Yes
Improved pairing (without a PIN)				Yes
Greater security		Yes	Yes	Yes

Aside from these different versions of Bluetooth specifications, there are also quite a number of different Bluetooth profiles. A Bluetooth profile is an interface or a behavior through which different Bluetooth devices can communicate with each other. Both devices must support the same profile in order to communicate with one other in that way. The most common Bluetooth profile in cell phones is the Headset profile (HSP) which supports the use of standard mono headsets for making calls. Here's a list of the more frequently used Bluetooth profiles in cell phones, as described by the Bluetooth SIG:

• Advanced Audio Distribution Profile (A2DP)
  Also widely known as the stereo Bluetooth headset profile, A2DP allows for a dual-channel audio stream through a stereo headset. A2DP is an especially popular concept with MP3 and music phones because it lets users listen to music wirelessly. It also can be used to make calls, and users can switch between music and calls at the touch of a button.
  
  
• The Sony Ericsson K790a is a phone with stereo Bluetooth.
  Audio/Video Remote Control Profile (AVRCP)
  AVRCP provides a standard interface to control TVs, hi-fi equipment, and so forth. This profile is used to allow a single remote control (or other device) to control all the AV equipment to which a user has access. AVRCP defines how to control characteristics of streaming media. This includes pausing, stopping, and starting playback and volume control as well as other types of remote control operations. Some Sony Ericsson phones have this profile built right in. An example of one is the Sony Ericsson k790a.
  
  
• Dial-up Networking Profile (DUN)
  DUN enables access to the Internet and other dial-up services over Bluetooth wireless technology. The most common scenario is surfing the Web from a laptop by dialing up via a mobile phone, wirelessly.
  
  
• Hands-Free Profile (HFP)
  HFP lets you use a gateway device to place and receive calls for a hand-free device. A typical configuration is in an automobile using a mobile phone as a gateway device. In the car, the stereo is used for the phone's audio and a microphone is installed in the car for sending outgoing audio of the conversation. HFP is also used for a personal computer to act as a speakerphone for a mobile phone in a home or office environment.
  
  
• Synchronization Profile (SYNC)
  The SYNC profile is used in conjunction with GOEP (Generic Object Exchange Profile) to enable synchronization of calendar and address information (personal information manager, or PIM, items) between Bluetooth-enabled devices. A common application of this profile is the exchange of data between a PDA and computer.
  
  
• Object Exchange (OBEX) Protocol
  OBEX is a transfer protocol that defines data objects and a communication protocol that two devices can use to exchange those objects. For Bluetooth enabled devices, only connection-oriented OBEX is supported.
  
  
• SIM Access Profile (SAP)
  SAP allows devices such as car phones with built-in GSM transceivers to connect to a SIM card in a Bluetooth-enabled phone. Therefore, the car phone itself does not require a separate SIM card.

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