I just attended today at Von.x a panel on Femtocells with execs from 2Wire, Kineto Wireless and NextPoint. A femtocell is basically a wireless home gateway that boosts the cellular signal in your home. There are 2 ways at doing this, the T-Mobile way (UMA) and the Sprint way (with the Samsung femtocell pictured).

- The T-Mobile HotSpot @Home service uses the subscriber existing Wi-Fi home network to connect a T-Mobile dual-mode phone (GSM/Wi-Fi) back to the T-Mobile cell network. This solution uses a "UMA" client on the cell phone that takes care of all the configuration, routing, hand-over, etc;

- On the other hand, the Sprint Airave service requires an additional $50 device, the Samsung femtocell, that will act as a small cell tower in your home and will connect back to the Sprint core network using your existing broadband connection (cable or DSL). The service costs $15 per month for an individual and $30 per month for a family plan.

The UMA solution is faster to install than femtocell's

The advantage of the T-Mobile solution is that it uses your current Wi-Fi equipment at home and that the service only costs $10 extra, on top of your current T-Mobile bill.
But the main drawback is that you need to change your cell phone for one of T-Mobile's limited dual mode, GSM/Wi-Fi, cell phones selection. For some of us, who have iPhones or some other "esoteric" phones, that's a no no.

Femtocell solutions will work with your existing cell phone

For example, a femtocell Sprint base station will work with Sprint phones, AT&T femtocells with iPhones, etc...
However, you will have to install/manage/support a new "box"/gateway in your home that will emit yet more airwaves in addition to your Wi-Fi router and all the other airwaves flying around your home.

But the real huge drawback for femtocells' success is the interferences they will cause to wireless carrier networks, especially if thousands or millions of those cell base stations are installed around the country. This is probably the single biggest headache for wireless engineers to solve before any carrier plan a large scale roll-out of femtocells.

So who's winning?

At this point, UMA has a head-start because of its simplicity and low cost. The wireless carrier will subsidise the dual mode phone anyway.

1) Most of subscribers change cell phones every year anyway;

2) There will be more dual mode phones on the market and most of the manufacturers have already started shipping them in volume: Nokia, Apple, RIM but not Palm.

But expect to see wireless home gateways with femtocell commercially available next year. By this time, wireless carriers expect to solve the issues of interferences.