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January 2008 | Volume 11/ Number 1
Feature Articles

Fixed-Mobile Convergence Meets IMS and UC

By: Richard “Zippy” Grigonis

The concept of Fixed-Mobile Convergence (FMC) made its debut at the 2005 GSM World Congress in Barcelona. Enterprise FMC – also called Mobile Unified Communications by IP PBX vendors, to distinguish this type of FMC from the carrier-based variety (e.g. T-Mobile and Embarq) favored by consumers – extends IP PBX services to mobile users, be they in the office or outside the office. Ideally, a system can move a call from a desktop phone to a dual-mode mobile phone, which can in turn move seamlessly from WiFi coverage in the office to cellular service in the great outdoors. (A dual-mode phone isn’t necessary if you can tolerate calls being transferred between devices.) Since various network elements are needed, such as Session Border Controllers (SBCs), Gateway GPRS Support Nodes (GGSNs) and Tunnel Termination Gateways (TTGs), FMC needs to generate some revenue right off the bat, which is why FMC systems are to be infused with all sorts of tantalizing multimedia features and services, particularly anything to do with video.

IMS (IP-based Multimedia Subsystem) is a common service infrastructure for wireless and wireline providers that will help providers hatch lots of new “de-siloed” or “non-stovepipe” services and deploy them inexpensively. Although IMS isn’t exactly the same as FMC, FMC is based on the 3GPP/3GPP2 IMS network architecture standards and FMC certainly contributes to the things that can happen in IMS, particularly VCC (Voice Call Continuity) which takes care of the handover of a call from WiFi (or any VoIP-capable wireless network access scheme) to cellular (GSM, UMTS, CDMA).

The original underlying assumption was that IMS would be all-IP, but of course we still have circuit-switched 2G wireless and TDM-based landlines. “Handover” or “handoff” between domains must therefore take into account session continuity and QoS (Quality of Service) as a user and a live call traverses today’s hybrid network. Ironing out the details in this area are companies such as Stoke ( and its Intelligent Multi-Access Session Management solution that can support subscriber calls within and across fixed, cellular, WiFi and WiMAX access networks.

Classic VCC will handle transitions between existing circuit-based core and IMS-based voice core until native, real-time VoIP services are established over macro networks.

Many network operators, carriers and service providers worldwide are building IMS-VCC networks. Vendors such as Nortel are running their equipment through interoperability testing. (In the case of Nortel, their portfolio in this area encompasses their Application Server 5200, Wireless Mobility Gateway 6000, Media Gateway Control Function, Packet Gateway Mobile Switching Center, Home Subscriber Server 1000 and Call Session Control Function 1000.)

Competing with IMS is UMA (Unlicensed Mobile Access), which provides GSM services over WLAN radio with built-in roaming and handover between wireless LANs and GSM wireless networks. Some consider this more of a stepping stone to IMS, since it provides connectivity to legacy services and doesn’t leverage SIP-compliant terminals, of which there now are many. Kineto Wireless ( is a leading supplier of UMA technology and has partnered with various companies in this area.

As we went to press, XO Communications ( and Sotto Wireless ( announced a trial for Seattle, Washington, of an FMC solution, Unwired Office, which combines XO’s nationwide IP network with Sotto’s integrated wireless and office phone communications service. Unwired Office is said to be the first, true single device (smartphone) FMC solution for businesses. The Unwired Office can be used in the office or on-the-go for voice, email and Internet access as well as by optional IP desk phones. It merges the office PBX, broadband network access and mobile phone service into a single, unified platform, yielding a similar communications experience for employees whether they’re either inside or outside the office.

Orange France also continues to make major inroads in FMC, having seen sales of dual-mode WiFi/GSM handsets increase by more than 50% in 3Q07. Indeed, by October Orange had sold 468,000 dual-mode WiFi/GSM handsets for its UMA-based services in France, the U.K., and Poland.

Ramping Up for FMC

As if feeling that there’s safety in numbers, vendors delving into FMC have been engaging in many partnerships and acquisitions. Avaya acquired Traverse Networks. Cisco bought Orative and announced a Nokia partnership. Research In Motion (RIM) bought Ascendent Systems.

Avaya is now certainly doing quite bit in the FMC market, having sold numerous IP PBXs over the years; it also has a home-grown FMC technology and strategy. Ironically, although U.K.-based BT announced its Fusion FMC service, it was Avaya that recently won the contract to provide the BAR Honda Formula 1 racing team with an FMC solution at its campus in Brackley, in central England, which will be capable of communicating with 18 other race circuits where they compete. The system uses Avaya’s Communication Manager Release 2.2 with cellular modifications that works with the BAR Honda IP PBX and application software in Nokia Series 60 phones that can route outbound mobile calls via the IP PBX.

And speaking of Nokia (, it appears to have made its way into quite a number of FMC partnerships, trials and deployments. For example, Nokia is working with Siemens Communications ( to enable Nokia’s dual-mode E series phones to work with Siemens’ Hi-Path Mobile Connect Solution so that calls can be handed off between WiFi and cellular environments.

In the case of FirstHand Technologies (, their extensive FMC expertise regarding smart cellular and dual-mode WiFi/cellular phones can be found working behind the scenes, in products OEMed by IP PBX companies such as 3COM, Nortel and 3Com. FirstHand’s new Enterprise Mobility Solution UC (Unified Communications) product release enables these IP PBX makers – as well as hosted VoIP providers and VARs supporting SIP interfaces – to quickly deploy an FMC supporting an extensive unified mobility and UC feature set that will work with many popular cellular and WiFi/Cellular dual-mode devices, including RIM Blackberry, Win Mobile 5 & 6 and the Nokia E-series. Available features include single number reach, visual voicemail, enterprise dialing, session mobility, corporate directory access, IM, presence, rapid conferencing, and seamless roaming between WiFi and cellular networks with automated WiFi-to-cellular handover and much more. The solution provides end-to-end security and policy-based mobility and feature access controls. Its standards-based interfaces include SIP/SIMPLE for IP PBX and presence systems, LDAP for directories and IMAP for Microsoft Exchange and voicemail systems. Thus, the Enterprise Mobility Solution UC should readily integrate into existing enterprise infrastructures.

Although FMC brings to mind new software-based applications, there are underlying hardware stories, too. Equipment vendors need to build products that not only meet today’s current needs, but also will provide some scalability and longevity so that service providers can cost-effectively furnish services for fixed-mobile, wireless and video applications. For example, Octasic ( recently announced its 15-core, 1.5 GHz, ultra low power DSP-based media gateway solution – named Vocallo – for voice, video and data over IP in enterprise and converged fixed-mobile carrier networks.

A Vocallo system is basically a complete G.729 gateway including full IP/RTP routing, carrier-grade echo cancellation, tones, message playback, conferencing, etc., with more than 240 channels per Watt and more than 40 channels per square centimeter of semiconductor space.

Vocallo’s media gateway software package includes packet-based wideband voice and video processing. Users can also add software in the Vocallo framework to differentiate their product with unique features. Developers and designers can also select the specific features, capacity and I/Os to meet their specifications. Thus, both features and capacity can be scaled (via licensing) to create a range of cost-effective products from a single design. Additionally, feature and capacity licensing can be extended to products in the field allowing for a Pay as You Grow scenario.

Carriers versus IP PBX Makers

IP PBX makers have a leg up on what carriers can do for the enterprise in terms of FMC, since IP PBXs are in many cases already on the premises, and their feature set can more easily be extended with their own expertise, using carriers as simply a form of transport, rather than carriers attempting to fiddle with existing IP PBX technology. This is why carriers have not been making a big splash in the market with their voice-oriented, mostly network-based FMC offerings. It’s a situation reminiscent of the traditional gulf between Centrex-like service providers and CPE-based solutions providers.

AT&T’s ( OfficeReach, for example, is a classic network service, having no special PBX hardware, installation, or license fees. It extends your common dialing plan to your employees’ mobile phones (not the desktop phone, interestingly enough). Therefore, it uses the employee cell phone number as the single, primary contact number when integrating your fixed and wireless voice communications (One Number Service). OfficeReach offers Zone billing - special rates when both parties are in a specific geographical area. Also, the service supports call screening to restrict certain calls for users or user groups, thus reducing distractions in and out of the office. A web-based tool can be used to control call restrictions and set up user groups.

Verizon ( also offers a roughly equivalent service, Wireless Office. It also uses the mobile phone number as the single extension in or out of the office. The service targets highly mobile teams that need to stay in frequent contact with each other and with their home office, or teams that roam around the corporate campus environment and are nearly always away from their desk phone. It also allows for the creation of closed user groups, call/no call lists and web-based management and maintenance.

FMC is obviously something that will bolster both IMS and unified communications, whether it’s delivered by service providers, enterprise equipment installations, or a combination of both.IT

Richard Grigonis is Executive Editor of TMC’s IP Communications Group.

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