Fixed Mobile Convergence (FMC) bridges cellular networks and WLANs

Fixed Mobile Convergence (FMC) technology allows wireless users to seamlessly transfer calls and call features from a cellular network to a WLAN and back again-one device, one phone number, and one voice mail box. Equipment manufacturers, wired and wireless carriers, and business customers are all considering how best to reap FMC's benefits.

Businesses, particularly those already using VoIP, are interested in the increased device flexibility, improved call quality, and potential cost savings that FMC offers. Using dual-mode phones (devices that can connect to both cellular networks and voice-over-wireless LANs), business users can roam between networks with a single device. When inside buildings and on the voice-over-wireless LAN (VoWLAN), users will experience higher call quality compared to GSM/3G cellular reception. Likewise, calls placed on the VoWLAN will not use cellular plan minutes.

Mobile Telephony (MT) providers are also carefully analyzing how FMC and dual-mode phone technology can help them improve profits and overcome the following challenges:

  • The burgeoning number of subscribers
  • Popularity of bandwidth-intensive applications, such as video streaming
  • Increased costs to build cellular network infrastructure

FMC can overcome these concerns by providing an alternative to cellular access, which reduces the load on the existing GSM/3G infrastructure. Once dual-mode phones gain traction, their benefits will touch MT providers as well as subscribers.

Sounds great, so what is the catch? The FMC technology required to seamless transition between networks is just now being deployed. There are dual-mode handsets available, a call can be made using VoWLAN or GSM/3G using that dual-mode handset, but to make it simple and reliable, the industry must overcome the following challenges:

  • MT providers and cellular/VoWLAN equipment manufacturers are in the early stages of developing the equipment standards and building the infrastructure required to facilitate FMC's widespread use.
  • Existing WLANs may need to be upgraded to support the bandwidth and QoS requirements of VoIP.
  • Dual-mode phones must have the same convenience and functionality as PBX desk phones.
  • Dual-mode phones have significantly less battery life when used on Wi-Fi network than when used on GSM/3G networks.

Even with the challenges, there are forward-looking companies are carefully considering the dual-mode telephony's benefits. NetworkWorld highlighted one such organization in its July 16, 2007 article, "Dual-mode deployments expected to spur VoIP on wireless LANs":

At outdoor retailer Gander Mountain, dual-mode phones could be a way to save on cellular minutes when traveling executives are at the headquarters building in St. Paul, Minn., or in stores, says Joe McClung, senior network engineer for the 110-store chain.

The company is swapping out Collubris Wi-Fi access points for those from Cisco, and that gives Gander the option to use dual mode, he says. In the meantime, sales associates in stores carry single-mode Wi-Fi phones to answer calls from customers. Incoming calls roll from wired phones, to Wi-Fi phones of associates to Wi-Fi phones of managers, he says.

FMC and dual-mode telephony appear to be on the verge of revising the concept of cell phone mobility. Yet, they aren't the only ball game in town. My next blog post will discuss Femtocell technology--an alternative to FMC and dual-mode phones that delivers similar benefits.