IMS in EPC ( Evolved Packet Core )

Timeline of Evolution 

GSM  : calls  on circuit switching ( CS ) between 2 parties for communication. Dedicated circuits are used for voice and SMS.

GPRS : packet switching (PS) is introduced for data services

UMTS / 3G : network elements begin evolving into PS . No changes to core .

EPC / LTE/VOLTE : No circuit switched domain at all .

IP Multimedia SubSystem was originally meant for evolved UMTS network to provider IP communication to mobile UAs. Today IMS is gaining plenty of attention due to oncoming

More information on IMS and IP Communication go here 

What is IMS or IP Multimedia System ?

•A standardized IP-based architecture that allows the convergence of fixed and mobile communication devices and multimedia applications.
•Using IMS, applications can combine voice, text, pictures, and video in call sessions, offering significant ease-of-use to subscribers and allowing service providers to drive branding through a common interface
•Defined by the Third Generation Partnership Project  (3GPP) and supported by major Network Equipment Providers and service providers.
•The standard supports multiple access types – including GSM/GPRS/EDGE, WCDMA, CDMA2000, wireline broadband access and wireless LAN.

ims arc1

 LTE ( Long Term Evolution )

 LTE evolved its precursor Universal Mobile Telecommunication System (UMTS), which in turn evolved from the Global System for Mobile Communications (GSM). It defines the access layer of Telecom architecture. EPC is the core of LTE system .
LTE is often linked with evolved UMTS terrestrial radio access (E-UTRA) and
evolved UMTS terrestrial radio access network (E-UTRAN). With this eco-system Evolved NodeB (eNodeB) is the base station for LTE radio.

What is EPC (Evolved Packet Core )  ?

EPC is a core network architecture framework by 3GPP.

 Primarily EPC has 4 sub parts

Serving Gateway
PDN gateway
MME (Mobility Management Entity)