I see that BT has finally announced some numbers for its Fusion service: "Following launch of the market leading V3B ( Motorola RAZR) phone, weekly customer connections have continued to rise, and reached over 2,000 for the week ending February 3, 2006, bringing the total number of Fusion customers to over 13,000" . I suspect this means subscribers rather than households - from a recent BT presentation I heard there are typically 1-point-something phones per Fusion hub. Let's say around 9-10,000 Fusion households.
Not exactly setting the world on fire, but roughly what I would have expected, given BT's stated softly-softly approach to introducing & tuning Fusion, especially prior to the WiFi version's launch in the summer.
My guess for the rest of the year? Given the WiFi launch, enterprise/SME Fusion and BT's general presence and marketing clout in UK mobility, I reckon by end-2006 (calendar, not BT FY) we'll be at about 70,000 Bluetooth Fusion users and maybe 140,000 WiFi-UMA ones, if they get the marketing packaging right.
As it stands, I'm quite happy keeping my June 2005-vintage forecast for UMA-based VoWLAN phone shipments in 2006 at about 600,000 globally, working on the assumption that US operator(s) launch in H2, and maybe a couple of other operators do some low-key soft introductions in Europe or Asia. There's possibly some upside here, if someone comes out with an ultra-aggressive package & subsidies (T-Mobile US?), but I'd be surprised to see more than a million leave the shelves under any realistic scenario.