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Unified Home Networks with the Fritzbox

by Guylhem Aznar

The Fritzbox is an all-in-one device from Such devices are quite popular in Europe, where operators usually bundle them with their "triple play" offers. These devices, also called home-gateways, provide DSL and VOIP connectivity to the operator, WIFI and LAN connectivity for the local computers, and telephone sockets (FXS) to connect traditional phones to a flat-rate plan. Many of them also offer digital TV service in high resolution (but not as good as HDTV). They are usually plug-and-play, and are owned and remotely manageable by the telecom operator. The Fritzbox is more than that.

Operator-Owned Devices

European-style leased devices satisfy most users but leave many geeks unhappy. What if you want to own your own hardware? What if you want to mix different offers from different operators? What if you do not want to ditch your PSTN phone service? What if you already have VOIP service? What if you do not trust your operator security setting? What if your operator does not yet offer such home gateways?

There are many scenarios where leased devices are not appealing. This is exactly the spot the Fritzbox tries to fill. Although specific telecom operator offers in Germany and in Italy do bundle it, the Fritzbox offers you freedom of choice. You can use your own Fritzbox with any operator and fine-tune your home network to your needs. If this is not enough, you can even reflash it with a custom-made GNU/Linux distribution.

Fritzbox Basics

The Fritzbox is many things. The best comparison is a small server without any screen or hard drive, running the Linux kernel on a TI Avalanche MIPS SoC. It has an AR7 providing a ADSL 2+-capable DSL modem, an ADMtek AMD9660 for LAN connectivity, between two and three FXS ports to connect your old telephones and--the best feature--a USB client or host. The system has 32MB RAM and 8MB flash. That doesn't sound like much, but it is more than enough for running a Linux kernel with proprietary software. The Cisco/Linksys WRT54G is comparable to the Fritzbox, with half its RAM and flash in the best case. Yet those restrictions rarely come up with the OpenWRT distributions for those needing an Access Point with advanced routing features.

There are two Fritzbox hardware versions, each with pros and cons.

The Fritzbox 7050 offers three FXS ports but only has USB client behavior. This means you can hook up three different analog phones to it, each with its own configuration, but you cannot plug USB devices onto the Fritzbox. The USB client can only connect to a computer, for example, if you do not have an Ethernet NIC. However, most computers, even laptops, now feature one.

The Fritzbox 7140 offers only two FXS ports but comes with a USB host. This means you can hook up a USB printer or a hard drive to your Fritzbox. This is potentially interesting if you want to share your printer on your LAN, or want to use your Fritzbox as a standalone storage station.

The lack of a third FXS port is easy to bypass with the ISDN capabilities of each Fritzbox. ISDN is the European digital POTS network, with advanced features that allow you, for example, to assign a different number to each handset.

Note that there are two different types of Fritzbox hardware: annex A and annex B. "Annex A" devices are for DSL over ISDN countries, mostly German-speaking countries, while "Annex B" are for the rest of the world. Annex A Fritzboxes are generally cheaper, yet are still usable in other countries after some firmware tweaking. However, this could potentially bring some DSL network problems and will void your warranty.

Real-Life Example

It is hard to explain everything you can do with a Fritzbox, so I prefer to give you a not-so-simple example: my own home network, before and after the Fritzbox.

Previously, I had an Alcatel Speedtouch Home Ethernet modem, which I had reconfigured to allow a direct PPPoE connection. This was a feature reserved to the Pro version, yet easily achievable on the Home version. This meant the Alcatel modem provided standalone IP connectivity to my LAN.

However, because it had only one RJ45 connector, I hooked it to a switch. On this switch, I had a small PC running a customized Leaf-Bering distribution from a 32Mb compact flash card to listen to French-Canadian radios at home. It had a USB port, which I used to mount USB keys for BitTorrent downloading though a USB hub.

Because I had laptops and a desktop computer in a different room, I plugged a Linksys WAP11 access-point into the switch to offer wireless LAN connectivity. My final device was a Grandstream HT-286 ATA that offered VOIP to a dedicated phone in order to have a Nevada area code phone number for friends who wanted to call us without paying outrageous transatlantic fees.

That was quite a setup mounted into a custom-made plastic shelf, hidden behind the sofa. It ate energy and ran quite hot. It was also awful to maintain, with so many power adapters and network cables. Taking incoming calls was a matter of picking up the right phone, which, thanks to Murphy's Law, was always the most distant one. Did I mention the phones also had their own power adapters, thus adding to the loose-wire mix?


I really wanted to change my home network, but my French DSL provider initially did not offer its own home gateway. When it did, I heard horror stories about people with neither phone nor internet access when the network went down, so I decided never to ditch the PSTN, if only to have a reliable way to call emergency services or pass important calls even when the IP network is down. Finally, I discovered that many home gateways offered by competitors had weak and easy-to-crack security.

That was too much. Even if I did not want to keep the power-hungry beast that was hiding behind the sofa, I could not sacrifice its reliability (well, until one of its cables fell out, which often happened), sustainability, and security to a "better-looking" solution. I did not want to pay some monthly rental fee for the device, either. My significant other was strongly disappointed. She hoped we could get rid of all this stuff. Well, I hoped, too.

Then I heard about the Fritzbox on German forums and decided to give it a try. That was the chance to replace my overly complicated setup by a most efficient and easily manageable one.

I decided that there should be two devices maximum, so I also purchased a Panasonic KX-TG6502B cordless phone. It runs on the 5.8 GHz band and manages two lines on up to four handsets and a base station, with intercom capabilities.

Making It Easy

The Panasonic phone connects by two RJ11 cable to the two FXS ports of the 7050. The third FXS port connects to a fax machine, which exists only to scan documents because I prefer FAXOIP.

There are two buttons on each handset, "line 1" and "line 2." I have a French flat-rate VOIP ( connected to line 1, with an automatic PSTN fallback in case of failure. On line 2, I have a U.S. VOIP line with a Nevada local number, to call friends.

Because I receive many more calls than I send on line 2, I have since reassigned it to a different French flat-rate VOIP (, which I use as a business telephone number. As it is a business line, I configured it not to ring after business hours. I keep the U.S. VOIP line accessible with a special prefix (*123#); it rings on line 1 when there are incoming calls.

Caller ID works perfectly, even if it comes from different networks (French, U.S.) with different modalities (PSTN, VOIP). I can transfer calls from one handset to the other, with conference calls managed directly by the Panasonic phone.

All this would be quite complex to specify in technical terms, yet the end result is very user-friendly: it always works (thanks to PSTN fallback), lets you decide which line you want to use for outgoing calls (press the "line 1" or "line 2" button), lets you override this for specific occasions (special prefix), and does not disturb you when it shouldn't ring. When it rings, the phone takes care of the call (conference call, transfer) in any area of the home.

Best of all, it took less than ten minutes to set up. That's no match for a PBX. I have five phones (four cordless and one base station) all around my home connected to this setup. It always works!

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