enterprisefmc

Technology Perspective on Enterprise Fixed Mobile Convergence

This article analyzes the various technologies for Enterprise Fixed mobile convergence that support the full range of applications —voice, data, video, and messaging — using dual mode handsets that interface to both Cellular Networks and Wireless local area networks (WLAN). This article doesn’t explain the details of how the technologies are implemented by the various vendors. This article is the author' view point of evolution of these technologies.

The solutions for enterprise FMC can be broadly classified into 3 categories: PBX-based solutions; Cellular-network based solutions, such as Unlicensed Mobile Access (UMA); and IP-network based solutions.

In PBX bases solutions, the user will have all the benefits of Desk phone dialling from their handsets and will have presence applications on the handset. The user may have the best coverage while in the WLAN. But to have the full benefit of seamless mobility, each user needs to have a reasonable data and voice plan. Also for handover from Wi-Fi to cellular to be effective, PBX needs to anchor the call. The benefits can be for global enterprises with employees needing the PBX features on their handsets all the time, from the remotest locations. WLAN may give a better coverage when there is poor cell coverage. This solution is inevitable as it offers international calling from handsets from anywhere and large enterprises with great many number of international business travellers find it ubiquitous. EnterpriseFMC is going to gain critical mass very soon using this solution. Agito Networks is the prime owner of this solution.

Unlicensed Mobile Access or UMA is a network based solution. It works great and enterprises can also implement this for handover between Cell and Wi-Fi networks. This is particularly useful in public hot spots and in international roaming. Since UMA is standardized, this technology would definitely lead to widespread adoption. But as far as the Enterprise usage is concerned, the user experience is still limited to the handset experience with no corporate dialing features from handset. Also this technology is not trivial to integrate with Next Generation IP Services.

The third and another Network based method is long term oriented and can easily be implemented for Next Generation Applications. This technology works based on a Mobility Server which sits adjunct to the core cell network The implementation is like a Visitor Location Register (VLR) for Wi-Fi based VOIP calls. A VOIP gateway in the MSC (Mobile Switching Center) registers the IP interface of the phone and performs from/to handoffs from the Wi-Fi domain. Interworking with the Cellular network uses existing Signaling System #7 (SS7) interfaces. The server works as a SIP “back-to-back user agent,” allowing both legs of the call (handset to network and network to calling party) to be held in place independently. Since the Mobility Server is SIP based, an ISC interface can be easily added to this server. When cellular providers migrate to a 3G air interface capable of end to- end voice over IP (VoIP) with IP Multimedia Subsystem (IMS).,seamless mobility can be easily added through the Mobility Server’s ISC Interface. The solution is flexible enough to bring all users to the same service platform; for example, both IP-Centrex or IPPBX solutions can be supported with simplified number planning because call routing only needs to be provisioned and managed in one centralized system.While this architecture supports SIP-based handoff of calls between existing cellular networks and Wi-Fi networks, it can be extended to cover other options, such as UMA-based, CDMA-based, future networks (e.g., WiMAX), and other legacy networks, including plain old telephone service (POTS).At this point of time this technology remains a proof of concept solution only, as there are no production ready IMS deployments yet . The context of IMS may be receding as other technologies are redefining FMC.

- Narasimha Vadrevu

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