FRITZ!Box

FRITZ!Box is a series of residential gateway devices from the German company AVM GmbH.

Functionality

There are several FRITZ!Box models available, but the most popular are the ones that combine DSL and SIP VOIP. The "FRITZ!Box Fon WLAN" for instance combines the following functionality:

* DSL modem
* Router
* Network switch
* Wireless access point
* PABX for both ISDN and POTS phone lines, and for both ISDN and POTS phones
* Session Initiation Protocol VOIP functionality
* Analog telephony adapter for both ISDN and POTS phones
* USB Ethernet adapter to plug directly into a laptop's USB port

Versions

Most FRITZ!Box devices come in three versions:

* German version for Germany
* German version for Austria and Switzerland
* International (English) version

Beside the obvious different language on the web interface, they also differ in the fact that the international version is available in two ADSL standards: ITU G.992.1 Annex A and ITU G.992.1 Annex B. The Germany version is only available as Annex B. This is due to fact that Annex A is not used in Germany (in Germany both analogue and ISDN lines use Annex-B ADSL, while in most of the world Annex-A ADSL is used on analogue lines and Annex B ADSL is used on ISDN lines).

The difference is in the use of the available frequency spectrum of analogue telephone lines (POTS).

Spectral allocation of services in a typical telephone line (from low to high frequencies)

--ANALOG--|---------ISDN---------|---------------------------------------------------DSL---------------------------------------------------

The Annex-A mode is more efficient since it uses the whole available (ISDN+DSL) spectrum. It allows for longer distances from the central DSL Access Multiplexer (DSLAM) to the subscriber. In Annex-B mode the ISDN range is spared (wasted), even for ADSL-Over-Analog subscribers.

The Fritz!Box can be changed [2] from German/Annex-B to English/Annex-A and vice versa by firmware. For the newer models the available international firmware updates may be somewhat behind the newest German ones.

ee also

* ADSL
* Router
* Voice over Internet Protocol

External links

* [http://www.fritzbox.eu Official website]
* [http://www.ip-phone-forum.de/showthread.php?t=97250 Converting a German targeted Fritz!Box Fon Wlan to an International version]