Universal Mobile Telecommunications System is among the third-generation mobile telecom technologies, which also became a 4G technology. The 1st deployment of the UMTS is the release99 (R99) design.It is specified by 3GPP and is a component of the world ITU IMT-2000 standard. The most typical type of UMTS uses W-CDMA (IMT Direct Spread) as the base air interface but the system also covers TD-CDMA and TD-SCDMA (both IMT CDMA TDD).

Being a total network system, UMTS also covers the radio access network (UMTS Earthly Radio Access Network, or UTRAN) and the core network (Mobile Application Part, or MAP) alongside authentication of users through USIM cards (Customer Identity Module). Unlike EDGE (IMT Single-Carrier, based totally on GSM) and CDMA2000 (IMT Multi-Carrier), UMTS needs new base stations and new frequency allocations.

However, it is tightly related to GSM / EDGE as it borrows and builds on ideas from GSM. Further, most UMTS handsets also support GSM, permitting continuous dual-mode operation. UMTS is frequently promoted as 3GSM, stressing the intimate relationship with GSM and differentiating it from competing technologies. The name UMTS, introduced by ETSI, is generally utilized in Europe. Outside the system is also known by other names like Foma or W-CDMA. In promoting, it is sometimes just called 3G.

Features of UMTS:-

UMTS, using 3GPP, supports maximum unproven data transfer rates of twenty-one Mbit/s (with HSPA),although currently users in employed networks can look forward to a transfer rate of up to 384 kbit/s for R99 handsets, and 7.2 Mbit/s for HSDPA handsets in the downlink connection.This is still much larger than the 9.6 kbit/s of a single GSM error-corrected circuit switched info channel or multiple 9.6 kbit/s channels in HSCSD (14.4 kbit/s for CDMAOne), and in competition to other network technologies like CDMA2000, PHS or WLAN offers access to the net and other info services on mobile devices. Predecessors to 3G are 2G mobile telephony systems, like GSM, IS-95, PDC, CDMA PHS and other 2G technologies employed in different nations.

In the case of GSM, there's an evolution trail from 2G, to GPRS, often referred to as 2.5G. GPRS supports a better info rate (up to a unproven maximum of 140.8 kbit/s, though everyday rates are nearer to fifty six kbit/s) and is packet switched instead of connection orientated (circuit switched). It is employed in several places where GSM is employed.

E-GPRS, or EDGE, is another evolution of GPRS and is based upon newer coding schemes. With EDGE the particular packet data rates can reach approximately 180 kbit/s. EDGE systems are commonly referred as "2.75G Systems". Since 2006, UMTS networks in several states have been or are in the act of being upgraded with High Speed Downlink Packet Access (HSDPA), occasionally known as 3.5G. Now, HSDPA enables downlink transfer speeds of almost twenty-one Mbit/s. Work is also progressing on bettering the uplink transfer speed with the Fast Uplink Packet Access (HSUPA).

In the long term, the 3GPP long-term Evolution project to move UMTS to 4G speeds of 100 Mbit/s down and fifty Mbit/s up, employing a new generation air interface technology based on Orthogonal frequency-division multiplexing.