Unified Communications

In the old days (1990s) of “unified messaging” a big, overarching program had to be written to gather email, voicemail and faxes into a single inbox and enable a response. It was assumed that the user was tied to the desktop. Indeed, at the time, that was touted as a ‘feature’ (e.g., “Day traders! You don’t have to walk to-and-from a fax machine anymore!”). Today, the concept of FMC (Fixed-Mobile Convergence) has brought mobility to UC, via the 3GPP’s VCC (Voice Call Continuity) specifications describing how a voice call can be maintained as a user’s mobile phone (usually conceived of now as a dual-mode device) moves between circuit-switched and packet-switched radio domains. This occurred first in the form of UMA (Unlicensed Mobile Access) for GSM/WiFi (News - Alert) roaming, and now the larger, more general IMS (IP-based Multimedia Subsystem) architecture, which itself allows for more services to be added to those accessible by UC systems, opens up the possibility of triple-or-more-mode phones that could switch among various kinds of networks in an ad hoc manner.