International Telecommunications Union (ITU) has published a ‘whitelist’ of only 11 mobile phones that are compatible with Bluetooth®-enabled hands-free telephone systems in vehicles.

All handsets were tested by German-based HEAD acoustics GmbH, and only the 11 made the cut on the basis of ITU-T Study Group12 standards P.1100 for narrowband (3.7kilohertz) and P.1110 for wideband (7.4kilohertz) speech quality through hands-free kits in cars.

The 11, which passed the 2014 test, constituted about 30 per cent of the phones tested. The remaining 70 per cent were found to produce performance degradation that would be noticeable to drivers and conversational partners.

"The worst performing phones showed some serious defects: some causing significantly distorted speech, others completely failing to acknowledge connection to a vehicle’s HFT (hands free terminals)," the report said.

Blackberry topped the whitelist with four of its handsets, Q10, Z30, Z10 (10.2.0.690) and Z10 (10.2.1.2102) meeting mainly the narrowband requirement. But Z30 made both the narrowband and wideband standards.

Motorola came second with two different versions of its Moto G  ”‹handset. Moto G KLB20.9-1.10-1.9 met the narrowband standards, while Moto G    KLB20.9-1.10-1.24-1.1 met the wideband requirements.

Sony Xperia Z1, LG G2, and HTC One M8 met both the narrowband and wide and standards, while Samsung S5 and Sonny Ericsson W880i met only the narrowband standards.

A statement from ITU, signed by Chief of Media Relations and Public Information, Sanjay Acharya said the list will assist consumers and automakers in determining which mobile phones are optimized for high-quality voice conversations in the hands-free environment of vehicles.

It said a mobile phone connected via short-range wireless communication (Bluetooth®) to a vehicle's hands-free telephone system must satisfy certain requirements to achieve high-quality voice conversations.

The ITU is therefore encouraging all mobile phone manufacturers to follow the requirements of relevant ITU-T standards and to participate in ITU testing events that analyse the behaviour of their products in conjunction with vehicle HFTs.