By Magda Engelbrecht, country manager at Nortel

The rapid growth of WLAN deployments in enterprises, hotspots and the home; the improving ability of WLAN access to provide high-quality voice service; and the introduction of dualmode handsets that support both cellular (GSM, UMTS or CDMA) and WLAN radio are creating new market opportunities. 

This will enable service providers to deliver a comprehensive service that converges mobile and fixed-line infrastructures, beginning with voice.  
Fixed Mobile Convergence (FMC) often describes two distinct groups of functionality. Firstly, FMC can provide services to a single device over multiple access types, such as cellular (GSM, UMTS and CDMA) and wireless broadband IP (WLAN and WiMAX).
Secondly, FMC can offer a single blended service to many devices, such as cellular phones, fixed devices and soft clients.
FMC solutions combine both groups in a way that breaks the link between the phone number, the network and the device. This enhances the ability to communicate as well as productivity controlling and simplifying the way people communicate.
The key to a successful fixed mobile convergence deployment is the intelligence in the heart of the network. There are hundreds of ways to integrate different devices and access types, but the resulting end-user experience must be made simpler and richer.
FMC solutions should feature advanced network intelligence and services based on SIP technology that are proven in commercial deployments.
As well is delivering a rich set of multimedia services, the FMC solution integrates many devices and access types with key capabilities such as seamless handover, transfer of active calls between devices and intelligent alerting devices.
For the service-provider, FMC removes the traditional barriers to delivering services while increasing value in the network, leading to greater end-user loyalty.

FMC value

Fixed Mobile Convergence promises a superior user experience that is delivered cost-efficiently and with convenience. And FMC offers service providers the potential for advantages to attract customers. It extends an opportunity for service providers to enter new markets and bridge the wireless/wireline divide.
The industry sees video and multimedia as the means to capture customers and differentiate from client-centric solutions (e.g., Skype over WLAN) – in particular to take content from the existing world and customize it for delivery to mobile devices.
The key to a successful FMC deployment is for organisations to compete not on price, but on value-added services.

Three approaches to FMC

There are currently three primary approaches in the industry to delivering a converged seamless service: Unlicensed Mobile Access (UMA), VoIP Extension and IMS-VCC (Voice Call Continuity).

UMA provides GSM services over WLAN radio with built-in roaming and handover between WLAN and GSM.  While UMA may be appealing to GSM operators, there are a few drawbacks with this approach.
It applies only to GSM operators and It doesn’t provide any new end-user services, only connectivity to legacy services. It also doesn’t leverage SIP-compliant terminals, which are likely to be implemented on all WLAN-compatible terminals in the long term.

VoIP extension
Several service providers offer downloadable clients for dual-mode handsets that extend the end user’s subscription to the handset. Once out of WLAN coverage, though, the end user is back to normal cellular service.
It is a low cost solution to the end-user, easy-to-install overlay and gives the ability to add multimedia services. A large and problematic drawback is that there is no opportunity to provide roaming to cellular service – so users have a converged device but not a converged service as part of an enhanced service portfolio. It is a step toward convergence but not true convergence.


Voice Call Continuity, currently under development in 3GPP R7, extends an IMS network to cellular coverage and addresses handover. It provides seamless voice call continuity between the cellular domain and any IP-connectivity access networks that support VoIP.
It is the most comprehensive of converged service approaches in that it can work between any cellular technology (GSM, UMTS, CDMA) and any VoIP-capable wireless access.  IMS-VCC provides for the use of a single phone number (or SIP identity) as well as handover between WLAN and cellular.
It provides key advantages such as a single solution to target multiple markets and segments and enhanced IMS multimedia services, such as greater personalisation and control.
It also offers a seamless handover of voice calls between a circuit-switched domain and IMS, seamless integration with other VoIP networks and access to services from any IP device.