By Andre Moskal

Service providers worldwide are under tremendous pressure to deliver meaningful services that not only retain customers, but also attract high-value business subscribers. The competition from emerging VoIP service providers, cable operators, and other competitive network operators has led to increased customer churn, which in consequence increases costs and lowers overall profitability of existing services.

Remote mobile, home, and business locations represent important communication connectivity points for most people. However, each one of these connectivity points has its own network characteristics, requiring the user to be familiar with multiple communication devices and different user interfaces. The ability to deliver services that enable mobility, feature-consistency and an “always-connected” paradigm in a multi-access environment would have tremendous value for service providers, and encourage customer loyalty in an increasingly competitive marketplace. But this opportunity is not without significant challenges. Service providers must find a way to deploy services not only across their own disparate networks, but also across their partners’ and customers’ various access networks. Hence, service providers must make a tough decision on how to balance future-facing offerings of value-added services focused on a specific set of devices, such as emerging multimodal handsets, against the exploitation of the deployed base of fixed and mobile devices.

Developing a Relationship
Perhaps one of the most significant areas of recent market change is in the relationship between fixed and mobile voice services. Initially service providers viewed these two service types as independent, each serving their own respective market, with mobile servicesspecializing in addressing users demanding communication on-the-go for business or social reasons. As the price of wireless voice minutes fell during the 1990s, and as the mobile data services continued to struggle with mass market acceptance, mobile operators started targeting wireline subscribers as a source of their continuous growth, creating in turn a fixed-to-mobilesubstitution trend. Likewise, the appearance of unlicensed spectrum technologies, such as WiFi, and the tremendous growth of WLANs and Hot Spots created opportunities for the wireline service providers to offer mobility at an attractive cost to their own customer base. Hence, two types of service providers are driven by their own competitive pressures to collaborate in order to supplement their most valuable assets such as broadband access and ubiquitous licensed spectrum radio coverage. Operators that can supply fixed and mobile services can get some relief from voice call price commoditization, but it is clear that the emerging VoIP services will impact not only wireline voice pricing, but also wireless voice. The primary driver for VoIP is the deployment of low-cost broadband service to consumers and businesses, driven by the desire of emerging voice services providers to create another revenue source through Internet access. This same desire exists in the mobile space, and the result will be a reduction in the cost of mobile broadband capacity, eventually pushingdown the price of voice calls. The Internet has already provided the world with the first broadly accepted mass-market model for non-voice services, and IP data is the largest driver of change in the network today. In fact, providers worldwide are migrating all their services to IP backbones, both to lower overall cost through the elimination of multiple service technologies, and to prepare for a future in which all services will be delivered in IP form as part of the fixed mobile convergence (FMC) trend. The interest of wireless and wireline service providers in IP multimedia subsystem (IMS), licensed and unlicensed wireless spectrum, as well as the increased number of multi-mode handsets, are all proof points that FMC is a real and current phenomenon. There is no alternative for any voice provider other than to embrace FMC, and find a way to profit from it.

Creating Linkages
FMC is a strategy that creates linkages between wireless and wireline voice services, meaning features that either migrate between the two services, or work by coordinating user behavior across both services. There are a number of applications that can be based on FMC, including:

• Call routing and disposition in the context of network presence, where an FMC user can select which service is to be used to complete calls, or have the call direction default based on the user’s presence within a multi-access environment.
  
• Multimodal handsets, offering both WiFi and cellular capability that can be used as extensions of a VoIP service on home/enterprise WLAN networks or as standard wireless handsets when no private network is within range.
  
• Device changes during an active call, including cellular to wireline (VoIP or TDM) or vice versa; used either for consumer convenience or to provide a backup mechanism for cellular services, should those services be unreliable due to the poor in-building coverage.

The industry has taken a number of different approaches to FMC. They include PBX-based adjuncts, cellular network-based emulation, and IMS networkbased solutions as described in this article. For some time now enterprises have been demanding effective solutions from the IP PBX vendorsto reduce the expenses related to mobility and roaming charges. Major IP PBX vendors already provide “on-net” wireline services for optimal call routing and are in the process of introducing solutions in partnership with handset and WLAN equipment manufactures to address these requirements for mobile users. Although in high demand, the existing solutions fall short in addressing truly seamless handoff between enterprise WLAN and cellular networks, and require two-stage dialing to access IP PBX dial tone for voice supplementary services. Of course, the advantage of this type of solution is the ability to use dual-mode handsets as extensions of the IPPBX while within the enterprise WLAN coverage. The dominant cellular emulation-based solution is unlicensed mobile access (UMA) delivering GSM voice and GPRS mobile data services over WiFi. The solution is based on emulation of the base station controller (BSC) that is managing a WLAN access network and interconnects to the core GSM/GPRS networks as a typical BSC. Because of the soft handover capability between the BSCs, UMA solutions offer seamless handover and consistent user experience regardless of the cellular or WLAN access. So far, UMA has been the only FMC technology standardized as part of 3GPP activities. Of course, there are a few disadvantages to UMA. Namely, it is difficult to integrate UMA within the enterprise environment due to the lack of straightforward integration with SIP. The current viewpoint among service providers and vendors alike is that UMA has a limited life span as an interim solution, and that in the long term it will be replaced by the IMS-based approach. To support consistently new value-added services in a core IP network, a new standard architecture called IMS has been defined by the 3GPP and adopted by the 3GPP2 organization. IMS also facilitates service convergence in the fixed line networks and it has been defined as open, multi-media service architecture for mobile and fixed networks using SIP as a unifying signaling protocol for voice and multimedia sessions. Although current IMS standards are still in the early stages when it comes to defining interaction between fixed network services (such as IP PBXs) and mobile services, the IMS framework greatly reduces the complexity of integration.