By CNET staff
12/05/2009
URL: http://asia.cnet.com/reviews/mobilephones/0,39050603,39393816,00.htm

Over the last few years, Bluetooth headsets have become must-have accessories for salesmen, white-van men and anyone who spends a great deal of time on the road. The benefits of these hands-free, wireless devices are obvious, particularly as it's illegal to use a handset in many countries while driving. And just as the number of headsets has exploded, the number of Bluetooth mobile phones has increased as well. Integrated Bluetooth is now present in a broad range of phones--from high-end smartphones to low-end functional models.

A smidgeon of history

Before we delve into the different kinds of headsets, it may help to know a little about Bluetooth itself. Even though the technology has been around since 1999, many consumers are still confused as to what it is, mostly due to its odd name (after a tenth-century Danish king with an affinity for blueberries) and how it works. And though it may sound complicated, it's actually simple, inexpensive and easy to use.

Bluetooth technology involves two devices communicating with each other over low-frequency radio waves in the 2.4GHz range. No cables or wires are needed, as the only requirement is that both devices be Bluetooth-compatible. Unlike infrared ports, the connected devices don't need to be within line of sight, and unlike a phone-network data transfer, Bluetooth doesn't cost anything beyond the initial investment in the devices.

In addition to connecting a mobile phone to a headset, Bluetooth is used to connect PCs to keyboards and mice, handhelds to other handhelds, and phones to computers. Many cars are even equipped with Bluetooth so that you can use the car's audio system for hands-free phone use.

Pairing up

The process of connecting devices via Bluetooth starts with "pairing", where a headset and a phone search for and recognise each other. Once your connection is made and secured via a PIN, the two devices will "talk" to each other and exchange information. You can connect up to seven devices simultaneously at speeds of 500Kbps and up. Bluetooth does have limitations, however. Its range is limited to 10m, which makes it good for connecting a handful of devices, but not appropriate for an entire network of computers (you're better off with Wi-Fi for a network). Also, you can connect only devices that have compatible versions of Bluetooth (more on this later).

But while Bluetooth itself may be easy to understand, choosing a Bluetooth headset for your phone isn't so simple. The number of Bluetooth headsets continues to grow rapidly. Styles, features, performance and compatibility vary, so it's important to take the time to find a device that's right for you.

Features and profiles

Most Bluetooth headsets have basic call features like the ability to answer and reject calls, last number redial, and so forth. Since sound quality is a priority with headsets, more advanced headsets also feature dual-microphone noise cancellation for better sound quality. A relatively new feature is multipoint technology, which lets you connect up to two different devices at the same time. This is useful if you use one headset with two phones, for example. Headsets with multipoint technology include the BlueAnt V1. And speaking of innovative features, the BlueAnt V1 was also the first Bluetooth headset to offer full voice command control. This meant we could say things like "Call Home" and if you've programmed the headset to do so, it'll do just that. The voice command on the V1 is independent from your phone, so you can use it even with phones that don't offer voice dialling, like the iPhone for example.

There are multiple versions of Bluetooth, and not all Bluetooth specifications are the same, so you might want to make sure your two chosen devices will work with each other. All of the newer Bluetooth 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 dialling, call mute, and last-number redial.

In 2003, the Bluetooth Special Interest Group, 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. Bluetooth 3.0 High Speed with faster data transfer has also been announced recently and devices sporting the new connectivity standard are expected in the next nine to 12 months.

Specifications	Bluetooth 1.1	Bluetooth 1.2	Bluetooth 2.0	Bluetooth 2.1 plus EDR (Enhanced Data Rate)
Voice dialling	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-metre range	Yes	Yes	Yes	Yes
100-metre 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 behaviour through which different Bluetooth devices can communicate with each other. Both devices must support the same profile to communicate with one other in that way. The most common Bluetooth profile in mobile phones is the Headset profile which supports the use of standard mono headsets for making calls. Here's a list of the more frequently used Bluetooth profiles in mobile 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.

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 in. An example of two are the W705 Walkman and C902 Cyber-shot.

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 dialling up via a mobile phone, wirelessly.

Hands-Free Profile (HFP) HFP lets you use a gateway device to place and receive calls for a hands-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.

Synchronisation Profile (SYNC) The SYNC profile is used in conjunction with GOEP (Generic Object Exchange Profile) to enable synchronisation of calendar and address information (personal information manager 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-orientated 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.

Other Bluetooth devices

Bluetooth accessories for your mobile phone aren't limited to just headsets. One of the categories for mobile Bluetooth accessories is the Bluetooth speakerphone. Mostly used as replacements for expensive hands-free car kits or as mobile conference phones, these speakerphones usually emit far better sound quality than that of your mobile phone's built-in speaker. A couple that we like include the Sony Ericsson Wireless Stereo Speakers MBS-200 and the BlueAnt Supertooth 3. Another category is Bluetooth-enabled timepieces. One of the more recent and stylish one is the LG Prada Link.

There are also a few devices that combined the Bluetooth headset with a speakerphone. The Kyocera Wireless Bluetooth headset with Speakerphone is one such combo; the headset is inserted into the speaker slot to activate the speakerphone function. There's also the mVox Duo Communicator, which is both a speakerphone and a Bluetooth headset in a single device.

Other uses for Bluetooth may not be immediately apparent. Sony's PlayStation 3 uses Bluetooth to pair its wireless controllers with the console, but this also means you can pair a Bluetooth headset to the system and use it to communicate with other gamers during online duels and co-op matches.