Telephony: Clearing Some Fog and Noise

Just when I thought I was clear on fixed-mobile convergence (FMC), I got two new press releases that started another train of thought. They made me think that from the consumer’s point of view, the choices to be made as service providers offer the quad play are going to be confusing. Depending upon where you need the seamless tie between landline and cell phone, and who your favorite carrier is, FMC means totally different types of services.

Generically speaking, the concept behind all FMC offerings is simple. You make your phone calls using a dual-mode cell phone, and sometimes you are talking over a cellular carrier’s network, and other times you are talking over a landline service provider’s network. As a telephone user, you don’t notice when the transition occurs.

If you probe a bit deeper, however, you find out that it may pay to watch the icons on the phone screen. Depending upon which carrier you’re using, the rates will change. Also, the way they change will be different for voice than for a data application. Location, location, location But let’s forget about the pricing details for a minute, and concentrate on where the convergence is occurring. Most talk in cable has been about a residential or small business application, where the landline phone service is a wireless 802.11 (aka Wi-Fi) extension of PacketCable-based voice over Internet protocol (VoIP) through a multimedia terminal adapter (MTA) and cable modem. Knitting the seamless fabric of convergence is the job of a redesigned call management server (CMS) and elements of IP multimedia subsystem (IMS), in particular, the home subscriber server (HSS). The technology vision is that when you leave the 802.11 coverage area, the CMS sets up the signaling needed for your dual-mode handset to home onto the nearest cellular tower. The reverse happens if you originate the call via the cellular handset mode. At some point, WiMax may replace 802.11.

Vendors in our industry are pretty close to having production hardware to do the job. Arris Senior Director Jeff Brooks tells me that the Arris TTPM552 embedded MTA (EMTA) is targeted for the first half of this year, with two wireline ports, an Ethernet connection, and an 802.11 interface. The path to WiMAX is also marked. "Our early trials indicate that the 802.11 port could be used in a WiMAX mesh network," said Brooks, "but the question is how soon the WiMAX technology will be available for commercial use." The telco approach But cable telecom is not the only telephony market working FMC issues, and other markets have different implementations. Digital subscriber line (DSL) technology provider 2Wire is offering the telcos a DSL solution that puts mini-cell sites called femtocells in residential gateways. In this architecture, the dual-mode handset uses a cellular connection until it moves into the "wireless home zone" of the femtocell, where it hands off from cellular to the femtocell. The femtocell’s "backhaul" to the cellular network is the subscriber’s DSL connection. Here, the benefit being marketed is the improved in-home coverage for both universal mobile telecommunications system (UMTS) 3G voice and data services and code division multiple access (CDMA) 2000 evolution-data optimized (EVDO) 3G services. Pasquale Romano, 2Wire president and CEO, claims that the architecture provides uninterrupted mobile data and voice service that rivals fixed line quality and simultaneous coverage for up to four different handsets. Although the subscriber could still have a landline connection, the concept is to move the subscriber to one phone and one phone number for all services.

Lest we forget, business arrangements between landline carriers and cellular providers play at least as big a part in the success of FMC as the technical implementations. Agreements need to be in place to determine subscriber charges, how to allocate revenue, and how to put everything on one bill. Resolving this is tough enough when the landline company and the cellular company have common owners. If they are separate business entities, the hurdles are higher. Part of 2Wire’s sales pitch is that the telco will be able to offer cellular services in the wireless home zone for less than the cellular carrier because its costs will be less. Because the telco ultimately depends upon the cellular carrier for call completion, this two-tier pricing only works if the cellular company is in agreement. In addition, any solution that involves dependence upon another carrier’s HSS is controversial, since customer data must be shared. Enterprise telephony Enterprise telephony is another market looking at FMC, but from a different angle. It has always led the charge to new applications, from the early days of digital private branch exchanges (PBXs) to VoIP. One type of enterprise IP PBX is a service provider business service known as a hosted PBX, where the telephony switch is owned and maintained by the service provider and located in its building. Vendors in this segment are talking about IP PBX extensions using dual-mode handsets. In late March, Sylantro Systems announced a working agreement with handset software vendor FirstHand Technologies that homes the handset on either a cellular network or a hosted IP PBX via Wi-Fi hotspots. The FirstHand Mobile Console software communicates with the Sylantro Synapps Server platform in the carrier’s hosted PBX to set up a Wi-Fi connection to the PBX when Wi-Fi is available, or a cellular link if it is not, and manages the handoff.

Dave Hattey, president and CEO of FirstHand Technology, explained the value proposition of this configuration. "This allows Wi-Fi/cellular handoff (Voice Call Continuity) without having access to the wireless carrier’s HLR or HSS (home register)," he said, "It allows fixed-line carriers to mobilize enterprise extensions via any cellular carrier or even multiple cellular carriers in parallel without having specific arrangements (MVNO, etc) with them."

Notice that neither of the alternative FMC implementations uses IMS. Noise The rest of this column is an update on some technology we talked about in December 2006 for managing return path ingress. In partnership with Lindsay Broadband, which provided hardware, Proxilliant has moved from trials of its Cable Access Management System (CAMS) to commercial application in Texas-based Buford Media.

The selling point of CAMS, as you may recall, is its ability to characterize and track ingress and then allow an operator to shut off an offending return from the tap to the home until a technician can be dispatched. Ingress management is particularly important to Buford as it begins its VoIP service offering. Dennis Krumblis, Buford Media VP Engineering, pointed out that Buford committed to the Proxilliant solution because it is particularly applicable to his small, rural system.

"In a rural environment, longer physical distances between tap and subscriber mean you have a lot more chances to pick up ingress," he said. "CAMS will save us a tremendous amount of time by allowing us to remotely analyze foreign signals in our return paths and narrow down where we need to dispatch a technician. In addition, we can prevent further system degradation sooner than before, by being able to remotely turn off offending branches of the network." In smaller rural systems, one tech often serves several towns, and the time between dispatch and arrival on-site is often longer than in the city.

Proxilliant’s CEO, Rich Berthold, pointed out that the CAMS system also improves quality and decreases maintenance expense for two-way applications other than voice, such as gaming and future IP-based services. He noted that while each company will have its own business case, the ROI on CAMS is typically less than one year. Justin J. Junkus is president of KnowledgeLink and telephony editor for Communications Technology. Reach him at jjunkus@knowledgelinkinc.com.

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