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Softbank Mobile Corp, IMS Network, Japan

Key Data

In November 2006 Softbank Mobile Corp in Japan launched the first live IMS network over 3G. The network was powered by the IP Multimedia Subsystem (IMS) solution from Ericsson. The new IMS network has allowed the operator to launch new exciting 3G services for the technically demanding Japanese market. IMS provides a flexible IP network architecture, which enables the delivery and execution of real-time voice, video, and multimedia services across all types of networks and terminals.

The use of IMS empowers the network so that users can communicate with greater freedom using whatever services they like, without having to be concerned for what device or network they or their contacts have access to. IMS is access independent as it supports IP to IP session over wireline IP, 802.11, 802.15, CDMA, packet data along with GSM/EDGE/UMTS and other packet data applications.

With IMS, all network services from call control, to voice, data, and video are done over IP, enabling operators to provide, deploy, and maintain an enhanced range of services, quickly and very cost-effectively. IMS is a standardised reference architecture that consists of session control, connection control and an applications services framework along with subscriber and services data.


The end-to-end IMS system has been supplied solely by Ericsson. Services introduced include Circle Talk (push-to-talk) and HotStatus (presence, group list management). Under the contract Ericsson has provided all the infrastructure, system integration and support services. Softbank has both fixed and mobile content and access networks and is an ideal IMS user.

Ericsson IMS is an end-to-end solution that gives operators immediate revenue opportunities when evolving to all-IP operations. It enables seamless access to a wide range of new multimedia services across both fixed and mobile networks. Ericsson’s IP Multimedia Subsystem (IMS) includes a converged IMS core infrastructure, as well as application servers and service enablers for common functions that can be reused for multiple fixed and mobile applications.


The IP Multimedia Subsystem (IMS) is a standardised Next Generation Networking (NGN) architecture for telecom operators that want to provide both mobile and fixed multimedia services. It uses a Voice-over-IP (VoIP) implementation based on a 3GPP and 3GPP2 standardised interpretation of Session Initiation Protocol (SIP), and runs over the standard Internet Protocol (IP). Existing phone systems (both packet-switched and circuit-switched) can be supported.

IMS may be used not only to provide new services but all the services, current and future, that the Internet provides. In this way, IMS will give network operators and service providers the ability to control and charge for each service. In addition, users have to be able to execute all their services when roaming as well as from their home networks. To achieve these goals, IMS uses open standard IP protocols, defined by the Internet Engineering Task Force (IETF).

"IMS will give network operators and service providers the ability to control and charge for each service."

So, a multimedia session between two IMS users, between an IMS user and a user on the Internet, and between two users on the internet is established using exactly the same protocol. In addition the interfaces for service developers are also based on IP protocols. It has been said that IMS will truly merge the internet with mobile communications. IMS uses a combination of mobile technologies to provide ubiquitous access and internet technologies to provide appealing services.


The vision for the future for which IMS will be very useful is Fixed/Mobile Convergence (FMC). This means that people will use one phone with one number, address book and voicemail bank, they will be able to take advantage of cheap, high-speed connectivity in their fixed-line home or office environment and using the same handset have mobility outside in the wide-area mobile phone network. This vision would also include a seamless handover of calls between fixed-line and mobile networks.