The hybrid approach to fixed-mobile convergence (FMC) that produce wholesaler Anthony Marano has taken involves a few interesting configuration twists.

For fast seamless inter-network roaming between Wi-Fi and cellular networks around its facilities, the company uses Session Initiation Protocol (SIP)-centric CPE from Agito Networks. To gain offsite PBX-integrated Wi-Fi options (such as in the home or public hot spots), the company uses Unlicensed Mobile Access (UMA) service from its carrier, T-Mobile.

On its indoor Meru Wi-Fi network, one Service Set Identifier (SSID) is set up for the SIP traffic and another for the UMA traffic. Each SSID points to a different virtual LAN (VLAN), explains Chris Nowak, IT director at Anthony Marano.

Sales people are in the SIP VLAN for direct, faster connections to the PBX; UMA VLAN members point toward the T-Mobile central office.

Anthony Marano has integrated its UMA-enabled BlackBerry smartphones with its BlackBerry Enterprise Server and its unlocked, SIP-enabled Nokia smartphones with its Exchange 2007 Server. The integration allows the salespeople to sync their phones wirelessly with their contacts.

In the old days, using the now discontinued Motorola CN620 dual-mode handset and FMC CPE, “sales people had to visit the telecom department and sync over wires to update their contacts. This might seem nominal,” says Nowak, but it was problematic because each has 400 to 500 contacts to manage and refresh.

And some users have subfolders for contacts, which Microsoft Outlook Web Access (OWA) – a program that accesses e-mail, calendars and contacts that runs on users’ handsets – doesn’t discern.

And why the dual handset base?

Well, for one thing, there are no dual-mode Wi-Fi/cellular handsets that support both UMA and SIP, observes Nowak — something he wouldn’t mind having for streamlining his phone inventory. Nowak has purchased unlocked Nokia E51 and E61i smartphones for the 50-person sales staff from the downtown-Chicago Nokia Flagship Store for use with the Agito system — phones that aren’t available from his carrier.

But T-Mobile is OK with turning on service for the unlocked phones, “probably because of their international bent,” says Nowak. U.S. GSM-based carrier AT&T has not supported unlocked phones to date.

Joanie Wexler is an independent networking technology writer/editor in Silicon Valley.