WCDMA(Wideband Code Division Multiple Access) is a technology for wideband digital radio communications of Internet, multimedia, video and other capacity-demanding applications. 

WCDMA is a third-generation (3G) wireless standard which utilizes one 5 MHz channel for both voice and data, initially offering data speeds up to 384 Kbps.

Operators such as Vodafone, Singtel, AT&T and TIM have chosen WCDMA as their 3G solution.

WCDMA is also referred to as UMTS - the two terms have become interchangeable.

WCDMA is the 3G standard that most GSM carriers are moving to. Parts of the WCDMA standard are based on GSM technology. WCDMA networks are designed to integrate with GSM networks at certain levels. Most WCDMA phones include GSM as well, for backward compatibility.

WCDMA borrows certain technology ideas from CDMA, as the name implies, but is in fact very different and incompatible with phones and networks using "CDMA" technology.

In Europe and Asia, WCDMA is being deployed in the all-new 2100 MHz frequency band. In North America, WCDMA is being deployed in the existing 1900 MHz (PCS) and 850 MHz (cellular) bands.

(Source:www.phonescoop.com)