* 'Dual-mode' and 'convergence' defined
Exciting dual-mode devices and converged services are emerging in the wireless industry. However, given that the terms “dual-mode” and “convergence” mean different things to different people (particularly marketers), try to be as specific as possible in your research in matching the capabilities you need to the products and services that actually support them.
For example, here are a few ways to interpret claims of dual/multi-mode capabilities and convergence:
* Note the subtle difference between the terms “band” and “mode.” A mobile device can support a dual-, tri- or quad-band cellular radio so that a given user’s cellular service continues to work across the various frequencies allotted to cellular service in different parts of the world. Generally, a user ends up roaming onto a cellular network operated by one of his primary carrier’s partners when entering a new region or country. In this regard, roaming across different cellular networks is enabled, so, in effect, cellular networks in different frequency bands are “converged,” and they are accessible by a single converged device. Dual-mode, by contrast, indicates that a given device can connect to two distinctly different types of networks, based on different technologies (e.g., analog and digital, Wi-Fi and cellular).
* A handheld data device, smartphone, or PC can contain two or more radios for accessing a cellular network and a Wi-Fi network. This device would be considered dual-mode (or multi-mode, depending on how many radios are supported). In most scenarios today, using each network is a separate activity; sessions on each respective network are initiated and torn down and do not transfer from one network to the other when the user crosses a network boundary. The convergence going on here is the ability to access multiple kinds of nets from a converged device.
* Mobile VPNs enable data roaming among disparate cellular, Wi-Fi, and other networks. These require mobile VPN client software and a mobile VPN server at your premises. At this juncture, mobile VPN solutions address data session transfers (not voice), among different mobile networks to accommodate field service, transportation, public safety, and other highly mobile field personnel. Convergence here is among data networks using converged access devices, thanks to mobile VPN software.
* A mobile device with multiple radios that connect to different kinds of wireless networks hands off voice and data sessions seamlessly as users roam, say, between Wi-Fi and cellular. There is convergence in the device, convergence of the wireless networks, and convergence of voice and data (and, hopefully, billing). These are very early days for these capabilities.
* It is possible to extend PBX 4-digit dialing to mobile phones, have multiple simultaneous telephone rings so one phone number reaches the user anywhere, and combine cellular, Wi-Fi, and wired voicemail in a single mailbox. This is available today and represents feature and application convergence across private enterprise networks and public and private Wi-Fi and cellular networks. If you combine these capabilities with the seamless handover mentioned above, you also have device convergence, network convergence and, possibly, voice-data convergence.
Bringing these last two bullets together reliably and securely is in development, but is still a year or two off from mainstream availability.
