SCHAPPY — 7. January 2007, 2:27

Fritz!Box Fon (FBF) + FoIP works better.

Recently I noticed a new firmware for the magic box. After reading the release notes, I mentioned some comments about sending fax messages via Voice over IP (VoIP).

Months ago, I tried to use an old external Teledat Eumex 504PC to connect to the FBF’s internal S0-bus. Then I used the integrated ISDN-card of the Eumex to send fax messages (using the FBF as transparent gateway). It does not work properly, until now!

Based on the installed dialing rules the ISDN-card of the Eumex will be redirected via Internet regardless of the ISDN service tag “FAX” (ISDN service “Data” will not work!).

But it may be necessary to changed the used VoIP codecs priority list depending on potential prior modifications of the FBF. If have changed this list in former firmware versions, it seems that FBF would never change them regardless what you set in the web-frontend in audio-codec settings. Thus telnet your FBF, and watch your voip.cfg using nvi.

[code]nvi /var/flash/voip.cfg[/code]

Scroll down to the attribute audiocodecs and check its values. Unfortunately, I’ve used G726-32 or similar codecs with high priority which causes the fax messages to get interrupted after approx. 38 seconds (after upgrading to the new firmware version). So, that made me thinking and finally I changed the priority of supported VoIP codecs for voipd. Currently my priorized list looks like this:

[code]audiocodecs = “PCMA”, “PCMU”, “G729”;[/code]

After restarting the voipd now fax events work well with this scenario. Although they are no longer logged with service tag “Fax” most VoIP provider establish a well connection. Try to lower the fax throughput to G3 or less if it does not work at first.

To cut it short: You need PCMA enabled when you try to Fax the traditional way without using T.38. Additionally you cannot (not yet) use the FBF internal capiotcp_server to send fax messages via VoIP, because it currently does not enable bindings to the VoIP controller (ISDN and analog PSTN works, ctrl 1..3 resp. ctrl 1..4).

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