# An IP Multimedia Subsystem Services Proxy Gateway Based on a JAVA Dynamic Module System
## 1 Introduction  
In the IoT (Internet of Things) era of information and communications technologies (ICT) booming and maturing, a user may own many peripheral devices in addition to the owned self-mobile device (e.g., smartphone). Meanwhile, many emerging application services have flourished, such as IP Multimedia Subsystem (IMS) related application services.  
Cellphone users in the 2G era, who inserted a Subscriber Identity Module (SIM) card into a traditional mobile phone for communications services, opt to insert a Universal Subscriber Identity Module (USIM) card into a smartphone and enjoy the IMS based Voice over IP (VoIP) service in the 4G era or later. IMS, which is one of the critical cores of the next-generation network (NGN), is a platform on which multimedia application services are integrated for more IMS-based services in addition to VoIP emerging in the future [1; 2; 3; 4; 5].  
People wish to enjoy the same application services on these peripheral devices and the owned self-mobile device in their home or office. However, IMS services are accessed restrictively on a personal self IMS device in which the USIM card is inserted only. Therefore, these peripheral devices in their home or office can not access IMS services, in which such devices are called non-IMS devices. Forexample, the device for dialing or answering a Session Initiation Protocol (SIP) call during video/voice communications is the user's personal self IMS device only in which the USIM card is embedded rather than any communications device moved or preferred by a user. To overcome this problem, we present the IMS service proxy gateway with which a user in a trusty field domain; for example, home, enjoys IMS services such as communication by the IMS device at peripheral devices (non-IMS devices) instead of the personal personal self IMS device only.  
OSGi [6] technology, which is the dynamic module system for JAVA, was used in the development of the residential gateway in past studies frequently for the members of the home network to access multimedia. OSGi technology is a Java-based technical platform but lots of software components for processing image transmission are not activated with Java. Most works of literature employ the OSGi technology to deploy a gateway for smart home application or Internet of things (IoT), vehicular network and so no. [7; 8; 9; 10; 11; 12; 13]. Fewer works of literature employ it to handle the rich applications, such as multimedia. For example, [PERSON] et al. integrated DLNA (Digital Living Network Alliance) services into the OSGi framework in the extension program of multimedia video sharing on the DLNA local network through which the home media resources were accessed by users via the peer-to-peer (P2P) network [14; 15]. However, the applications with respect to video phone calls or even IMS services are still uninvolved despite lots of research for the management of multimedia services based on the OSGi framework. In 2018, [PERSON] et al. [16; 17] proposed the application server (AS) for IMS, named SANGN, which is based on the OSGi technology with Java Agent DEvelopment (JADE) framework. Nevertheless, the AS is only for an IMS device, not for a non-IMS device. Accordingly, to settle the problem of IMS services not available to peripheral devices (non-IMS devices) in a field domain, we employ the OSGi framework to deploy the proposed IMS service proxy gateway with which the users inside a trusty field domain, e.g., home, make use of peripheral devices in the field domain to enjoy IMS services, for example, communication session.