Since its emergence in 2005 year from 3GPP (Third
Generation Partnership Project), IP Multimedia Subsystem
(IMS) became standardized arhitecture for providing
circuit switched and packet switched services on one
integrated, total and summarized solution. Today many
Telecom operators are implementing, if they have not
already implemented it, IMS system to coordinate many
overlapping services from different arhitectures to one
integrated solution. IMS system uses a group of
standardized protocols (basis is SIP protocol), whether
they are from circuit switched networks or packet switched
networks, to offer many services to its customers and to
integrate mobile networks, internet and fixed telephony
networks with reduced operating costs of the whole
arhitecture and with ease of billing, charging and user
authentification and authorization