There’s a fascinating race brewing right now between two technologies that approach the same goal from different directions.


“Home-routing” my cell phone


That goal is this: When I’m at home, I would like my cell phone signal rerouted through my broadband connection. Currently, I switch to my home phone in order to get lower rates. But that’s inconvenient because

1) I have to remember to manually forward and un-forward my cell phone number.

2) I still need to have my cell phone handy for sending or receiving text messages.


I prefer using my cell phone because it is a more advanced device and I have invested a lot of time in making it work for me (e.g. learning navigation shortcuts, personalizing the features and maintaining the address book). On the other hand, my home phone is just a dumb terminal — I consider it in the same category as my toaster.


In addition, many people are forced to switch to their home phone because of poor cellular reception where they live. (Fortunately, I don’t have that problem.) If you have a reliable broadband connection at home with a flat rate (that you’re paying for anyway) it makes sense to use that for your at-home calls.


So home-routing of my cell phone is really about two things:

1) Making my cell phone the only only handset I need.

2) Using my home broadband connection to get better rates.


About a third of cell phone calls are made from the home (see here and here), meaning that this is problem worth solving. So much so that the industry has found two ways to get us there…



Option 1: Bring the phone to the network

If your cell phone is equipped with Wi-Fi capabilities, you can connect to your Wi-Fi router at home and use a VoIP provider to route your calls. There are several cell phone models already on the market that fit this criteria. They are sometimes called “dual-mode” phones — horrible name. This approach is also sometimes called “VoWi-Fi” or even “”VoFi”, short for “voice-over-WiFi”.


T-Mobile is the first carrier in the US to go down this road with their “hotspot@home” service which launched in the summer. Intro video here. There’s some speculation on when they’ll expand the program to include out-of-home hotspots as well.

The iPhone has WiFi capabilities, so it could theoretically make calls over that channel, but Apple didn’t include that functionality out of the box (probably because it would be counter to the interests of AT&T, their carrier partner). But, you can make calls over WiFi using an iPhone by installing software from TruPhone. Here’s a video of that in action.


2) Bring the network to the phonesamsung-femto.jpg
This is where “femtocells” come in. The idea is to put a mini cell tower in your home. Last week, Motorola announced that it has started trials of femtocells with an unidentified major European operator. (Rumors say that it is Orange.)

Sprint is leading the charge in the US. Here’s what their femto cell looks like:


Here, in no particular order, are some of the factors involved…


  1. Carriers like it.
    Femtocells lower OpEx costs by reducing the load the cell towers and by offloading the “backhaul” component of the call to the user’s broadband connection. (Backhaul is the connection between the tower and their central office.) I wonder what the user’s ISP will think about carrying all that extra traffic.
  2. WiFi-capable handsets are still very rare.
    But femtocells work immediately with all cellphones.
  3. Femtocells let carriers get more out of their 3G licenses.
    3G coverage is lousy indoors, especially for data. According to T-Mobile, the most common reason people switch mobile carriers is poor coverage in their homes.
  4. The WiFi standard is not optimized for power consumption.
    By contrast, femtocells actually conserve phone battery life. Chris Gilbert, chief executive of femtocell maker Ubiquisys, estimates that the battery life of phones working off of femtocells can be “more than 200 times longer”.



  1. You need to wait for your carrier to deploy Femtocells.
    And you could be waiting many many years for that — early deployments are just beginning now. But you can go out and buy an unlocked “dual-mode” cell-phone today.
  2. A femtocell locks you in to your carrier.
    Meaning you are at their mercy for calling rates. And you will probably have a multi-year contract for the unit, similar to the one you signed for your basic contract. The Wi-Fi approach puts more power in the hands of the user. The flip side of that is a tougher set-up process. See Dean Bubley.
  3. Femto cells are a bigger technical challenge.
    There was a great session on this at VON. I didn’t follow all the details but the bottom line is that there are two very sizeable challenges: 1) RF planning — managing interference between devices. 2) Network interaction — deciding which handsets “roam” on to the femtocell and under what conditions.
  4. WiFi routers are an easy sell.
    From a consumer’s perspective the end box looks about the same, but the WiFi router provides plain old wireless internet as well as phone service. Furthermore, WiFi routers are a very mature piece of consumer electronics that are already below $100.


A close race

The race between Femtocells and Voice-over-WiFi has so many factors, it’s hard to figure out who’s got the advantage. Daily Wireless calls it a “dead heat”. This race was a hot topic at the Fall VON conference. After I attended a panel and had some impromptu discussions, I realized that people get pretty zealous defending their side on this. For example, here’s an interview with Sprint’s Manish Mangal with VON magazine. It’s not quite “Mac vs PC”, but it is one of the juiciest debates in mobile hardware right now.



4 Responses to Femto vs WiFi

  1. Excellent assessment of the debate. The migration from fixed phone at a place (eg home) to cordless and then mobile is still in progress. Not only does my home phone also have the brains of a toaster, but my address book is not sync’d with it either.

    However, one point you’ve underplayed is the growth of mobile data services and the resulting costs of backhaul transmission for the carriers. For voice the data rates are pretty low, so relatively insignificant for broadband operators – the issue is the same as for VoIP ensuring QoS is maintained. If mobile data really takes off though, and laptops are used for general data surfing, then offloading the backhaul traffic (from the cellsites to the switching centres) to go over customers own broadband services (at their cost) makes for a good business proposition.

    You can find more information about the vendors and business proposition on my website.

  2. Shai says:



    Yes, the backhaul part is interesting – if I were the customer’s ISP and a competing wireless carrier put in a femto cell that dumped all the customer’s voice traffic onto MY lines, I would be upset. Probably call it a violation of ToS, and maybe even block it. On the other hand, many wireless carriers are also in the internet service business, and that turns things around: If I own both the wireless and wireline connection to the user then home-routing is win-win.

    - Shai

  3. [...] Femto vs WiFi debate (which I posted about here) really heated up at the World Mobile Congress in Barcelona last week. (Sounds like that show was a [...]

  4. Manthus says:

    Really nice consolidation of points. its worth reading.

    Thanks a lot

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