Fritz!Box Fon and differences in ADSL standards (Annex A & Annex B)
In the scheme below the spectrum from 0-4 kHz would be used for the telephone service, whereas 25.875 kHz to 1104 kHz is reserved for ADSL (divided in Up- and Downstream).
This sharing of frequencies for regular phone lines is specified by the ITU according to ITU G.992.1 Annex A.
However besides regular analogue telephone lines there is a digital telephone system called ISDN, which is mainly used for business purposes. ISDN requires more bandwidth than assigned by the named ITU standard for regular telephony. So ITU G.992.1 Annex B was passed, which defines another frequency usage for ISDN + ADSL.
When purchasing a FBF, like with an ADSL-modem or router, you need to know which Annex you need: Annex A for a regular phone line + ADSL or Annex B for ISDN + ADSL.
Luckily some of the FBF Annex B models, especially the older ones ("AVM Fritz!Box Fon (WLAN)", "FBF 5050" and "FBF 7050") can easily be switched to Annex A by a small patch.
However switching the opposite way - from an original Annex A FBF to Annex B - won't work. Anyway the Fritz!Box FON also supports ATA-mode, so it can be connected to an external modem (ADSL or cable) or to an ethernet network.
Switching to Annex A may be interesting for those, who prefer buying a used FBF from Germany (which are all Annex B versions) for less than NZD 100 (+ NZD 70 shipping) from eBay instead of spending more than NZD 500 at the official NZ distributor http://www.telephonesonline.co.nz.
As you can see from the screenshot below the frequency spectrum still looks fine after an Annex change from B to A on a German "Fritz!Box Fon WLAN", which runs flawlessly on an xnet.co.nz ADSL line:
Other related posts:
How to connect a Fritz!Box Fon in New Zealand
What's (so special about) the Fritz!Box Fon?
Comment by Colin, on 7-Aug-2011 12:47 , user id: )
Hi there. Have got hold of a fritzbox 7270 V2 from Germany but they did not send the cables. Are you able to tell me the pinouts of the 7270 cable so I can make my own?
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Comment by Sally Simpson, on 26-Mar-2008 15:32 , user id: )
If you buy for "more than NZD 500 at the official NZ distributor http://www.telephonesonline.co.nz" then you deserve to be ripped off by them.
There are way cheaper alternative distributors.