Mr. Peebles,

This radio interface increase in bandwidth that the femtocell delivers has to use somebody's backhaul resources.  If you have an Internet access service, then like as not, it will be using yours.  

Of course, it will not be paying you for the Internet access service bandwidth that it uses to get its calls back to its carrier's switching center.  If "your" femtocell is capturing mobile broadband calls, when backhauled through your Internet connection these calls will look just exactly like the 'bandwidth hogs" that are slowing down or stopping your e-mails, web browsing, video streaming, and the like.  

This is not exactly a hidden cost, but it definitely impacts the 'value' proposition you bought into when you forked over your cash for that femtocell.

It looks to me that nearly all the advantages of femtocells are with the operator and not for the customer.  One more issue:  You might be quite happy for a visiting friend to use your femtocell, but if you're using Vodafone and they're on T-Mobile, then this isn't going to work.  Meanwhile the visiting postman (using Vodafone) might come into coverage just because of your femtocell.  The network ownership questions are tricky.

As an ex-Dialogic guy, I was somewhat surprised to see a blog re femtocells - not sure of the connection with voice processing! My current company is heavily involved with femtocells (see www.epitiro.com/femtocells.html) and I thought I would set the record straight regarding any potential benefits and drawbacks.

From an operator point of view, there are a number of advantages, some of which have already been mentioned. For the record, these include low capex network expansion and bandwidth reuse, lower churn rates (churning would mean swapping out femtocells), the probability of capturing all users in the household and (due to presence detection) the possibility of offering advantageous tariffs when in the home, in order to capture more business from the fixed line operator. As for the backhaul, this is critical and needs to provide sufficient QoS for acceptable voice quality. However, if the data stream replaces what was previously connected via wifi, the incremental backhaul load of up to 4 channels of voice is relatively insignificant.

From a consumer point of view, the potential benefits include the convenience of using a mobile from home (with its directory and other advanced features compared to a pots phone) without paying extra for the privilege, and the potential of added value services such as automatic download of pictures and video clips when presence is detected. As for sharing the femtocell with visitors or the postman, the femtocell can be configured to only work with specific cell phones – this can be user or operator configurable.

Femtocells can also be used in remote locations – perhaps as a communal resource for a small village in emerging markets, with backhaul perhaps via Wimax.(802.16d).

Apologies, the web link in my comments above should have had a capital F in it, www.epitiro.com/Femtocells.html