1.通用移动电信系统(UMTS)：
UMTS代表基于3GPP标准开发的通用移动电信系统。它的网络由三个主要部分组成：UE(用户设备)，无线电接入网(RAN)和核心网。基于3GPP社区的不同版本，有多种技术属于UMTS。它也称为3G。
2.全球移动通信系统(GSM)：
GSM代表全球移动通信系统。它是世界上主要使用的移动通信系统。它使用时分多址访问(即TDMA)通过带有两个不同客户端数据流的通道向下传送数字化和缩减的数据，每个客户端数据流都在其自己的特定时隙中。
UMTS和GSM之间的区别：
| S.No. | UMTS | GSM |
|---|---|---|
| 1. | UMTS is already 3G. | GSM is 2G and 2.5G. |
| 2. | It is mainly CDMA-based. | It is typically based on TDMA . |
| 3. | There channels are divided into logical, transport and physical based on where they are used along with their functions. | There channels are divided into traffic channel and control channel based on functionality of use in the system. |
| 4. | Its frame duration is about 10ms, | Its frame duration is about 4.615ms, |
| 5. | It is newer. | It is a rather old technology. |
| 6. | It has various bands from Band-I to Band-VI, Each band specifies frequency and UARFCN. | It has various bands, the major among them are 850MHz, 900MHz, 1800MHz and 1900MHz. |
| 7. | It has various documents specified by ETSI and 3GPP, 3GPP™TS 45-series. | It has various releases such as R99(WCDMA), R5 (HSDPA), R6(HSUPA) etc. |
| 8. | The modulation efficiency is 1.0 b/s/Hz . | The modulation efficiency is 1.35 b/s/Hz. |