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  • Fax vs. Shoretel, odd results

    Greetings all,

    We've been struggling with inbound faxes redirected from users extensions to a MultiTech FF420 fax server connected to SG50's. We're starting to narrow down the problem. For some reason, if faxes hit the voice mail of a user (ie. after 4 rings) and then get re-directed, the faxes seem to fail more than if the users answers the calls and hears the beeps and waits for the Shoretel system to redirect the call at that point.

    This is starting to get pretty consistent, and we can't figure out why. When the fax machine hits the voicemail, it is FOR SURE being redirected to the fax server, as the fax log shows the incoming call. So I know I don't have a redirection issue. The issue more once the fax is redirected, then the pages are not fully received (usually just partial), but only when the redirection came by way of the voicemail vs. the user answering the call.

    We were running the 8.0 CR and then the 8.1 CR versions, but we recently upgraded to the gold 8.1 release and the problem still exists. The calls are coming in on an ATT PRI line if that makes any difference. QoS is implemented fully across the network, and the fax server is set to "fax server" in the Shoretel config's to insure the jitter-buffer is locked, etc. etc. (ie. we've made sure our config is all correct as much as we could.)

    Any help would be appreciated...

  • #2
    how are the modems configured on the fax server side?

    max baud rate?
    error correction on/off?


    • #3
      Great question, I should have mentioned that to begin with.

      Per Shoretel whitepaper, 9600 Baud, no error correction. I've also experimented around with other settings after trying 9600 NE and sometimes I've gotten better results, sometimes not.


      • #4
        excellent. which code are you running on the fax server and on the modems? we had some problems in the past that were helped by getting on more current stuff. that said, we still see as much as 10%-15% error rate.


        • #5
          Check your Codec. PCMU/8000 for fax bandwidth.


          • #6

            Thanks for replying back. We are running a Model FF420 with version 1.04E, which I believe is the latest code. We also have the firmware of the modems at the latest levels as well.


            We were using L16/8000 as the first priority, and then PCMU/8000 as the second. I'll try flipping these and see if it makes any difference.

            Any other ideas? Thanks in advance for any further help.


            • #7
              Just checked the codecs again. They are the default Codecs from Shoretel that can't be changed, and the L16/8000 is considered the "high" codec. The "low" codec has PCMU/8000 on it. I'll switch to the "low" fax codec just to try and see if my issues actually go away, but I'm doubtful. Again, thanks for the suggestion though.


              • #8
                We have the same exact setup and found the best luck with the High Fax Bandwidth Setting. We are down to 13% or so errors now.


                • #9
                  Urgh. I hate analog faxes. Why can't the industry just make a move to FoIP.

                  Still about the same, ~10% failure rate. Changed the DTMF delay to 4 seconds and that seems to have helped a little. Tried different codecs, not luck.

                  It's interesting though, we're still having the issue where if a user answers the call and the fax-redirect kicks in, that we get more failures than if the fax hits the voice mail directly. Go figure.