Page 435 - 5G Basics - Core Network Aspects

Core network aspects 1

Voice call continuity (VCC) is required in this scenario to provide ongoing call continuity between the cellular
CS domain and the IMS domain. When users with dual-mode terminal devices move between the two
domains, handover may happen from a cellular CS domain to an IMS domain or the reverse and no break is
perceived by users during the handover.

Enhanced VPN support is required in this scenario.
IMS-based FMC could in principle also support service continuity for video calls between the IMS and a
cellular CS domain. This capability is for further study.
IMS-based FMC may provide services to mobile as well as PSTN/ISDN terminal devices through IMS-based
PSTN/ISDN emulation. This FMC scenario is detailed in [ITU-T Y.2031]. Specific requirements for this scenario
are for further study.
10.2.2 FMC between circuit-switched mobile and PSTN networks

This convergence of fixed and mobile networks enables users to roam into the legacy PSTN network outside
a GSM/UTRAN or ANSI-41/cdma2000 network. The requirement to support that users roam into a PBX
network is for future study.

Limited mobility is supported, e.g., nomadism, but service continuity (handover) is not required to be
supported for this scenario.

NOTE – Technologies for access to the PSTN could be GSM/UTRAN or ANSI-41/cdma2000 radio technologies and local
radio technologies such as Bluetooth or Wi-Fi.
Voice communication services in this scenario are required to be supported using a single personal number
or user identifier. Video communication services could also be supported in this scenario.
GSM/UTRAN or ANSI-41/cdma2000 supplementary services are required to be supported when the user
makes and receives calls under PSTN access unless limited by PSTN network capabilities.

Enhanced VPN support is required in this scenario.
10.2.3 FMC in access network by UMA/GAN

This convergence of fixed and mobile networks to enable the provision of service continuity for a multi-mode
WLAN/2G terminal device when it changes its point of attachment is known as unlicensed mobile access
(UMA). Demand for such capabilities is driven by competition on price and user convenience and the desire
to extend service coverage in buildings with poor mobile radio reception.
UMA is also known as generic access network (GAN) [b-ETSI TS 143 318].
This scenario does not provide an evolution path to an all-IP NGN, since it keeps voice calls in the CS domain.
This scenario is for further study.

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