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  • Music On-Hold Distortion

    When a caller is put on hold, the music heard sounds distorted. This happens with an older cassette tape MOH player or a new digital memory MOH player (OHP 7000). And it happens when either player is plugged in to either one of our two ShoreTel 120/24 switches.

    I have adjusted the output volume of the OHP 7000 up until too loud and down to where the MOH can bearly be heard, but the sound is still distorted. I have also tried switching impedances on the OHP 7000 from 8 ohms to 600 ohms. This changed the output volume a little, but did not appear to make any change with the amount of distortion heard. (BTW, which is the correct setting?)

    I plugged a set of computer speakers into the output of the MOH 7000 and the sound is crystal clear (CD-like), so I believe the OHP 7000 is working correctly.

    I know that listening to music over phone lines is pretty inferior quality anyway, but I have sat on hold for extended periods of time with a variety of vendors and heard decent (AM-quality) music without distortion.

    What say you wizards of ShoreTel systems? MOH should be plug and play, correct?? What am I missing (be kind)?


  • #2
    Audio Input (Music on Hold) Cabling
    The ShoreGear-24, ShoreGear-12, and ShoreGear-Teleworker voice switches each have
    a 3.5 mm mini-mono input connector that provides music or some other recording to
    callers when they are on hold. The input port supports low-level line audio from a
    preamplifier or mini-CD player, at 47 kΩ nominal impedance. The audio input cable
    can be up to 10 feet long.
    The audio input port on the ShoreGear voice switches is a mono connection. If you
    connect a stereo input, the stereo signal is converted to a mono signal.
    To minimize bandwidth, music on hold is not streamed across the wide area network,
    so you will need one music source per site.

    This is out of the manual.

    Check your cable maybe is not the correct connector


    • #3
      I had complaints on our Shoretel system too. We minimized it by setting the equalizer all the way down on the low and high ends, leaving the mid levels flat or boosted a little. This seems to take away some of the noise. However, on mobile phone calls, the signal is digitized at another level which adds more distortion, but there is nothing we can do about that.


      • #4
        BraasRichB, I'm willing to bet you have an SGT1 switch for your trunks that this problem occurs on. I have been running into this issue, and have done a bunch of testing. It always occurs on the SGT1, and never occurs on any of the other switches I have access to test with.

        Another factor I have discovered: the issue only occurs when the person listening to the music on hold makes a sound. When I mute my phone, the distortion goes away 100%.

        I have set up a lab environment with two separate shortel systems, and connect the T1 an T1k switches with a crossover cable. I'm able to reproduce this problem easily. What's weird, is I have recorded the trunks and the T1 switch sending the MoH tx recording has perfect MoH, but the T1k switch recieving the MoH rx recording has crappy quality exactly whenever there is any sound in the tx.

        Can anyone out there verify this is what they are seeing?


        • #5
          We had a similar issue with our MOH source and it was the cable we were using. I installed a new one and it resolved the issue.


          • #6
            This is definitely not a cabling issue I'm seeing. I've replaced cables, tried different types, and made my own. It happens no matter what. I'll admit the ShoreTel documentation is pretty crappy in what it calls for here. In different places in the planning and install guide it states that this is a "3.5mm mini-mono" connector, then it states that it is a "3.5mm mini-stereo" connector.

            I've tested this, pretty thoroughly, and found that a 3.5mm stereo cable works reliably in all cases except when using that SGT1 switch as the trunk.

            Anyone else out there not able to fix this by replacing a cable?


            • #7
              What do you mean when you say 'using the SGT1 as the trunk?' What other switch would you be using besides the SGT1 or E1? (I'm not an installer, just admin).


              • #8
                I mean you could be using an SGT1k, SG220T1, or SG220T1A for T1 trunks. Or any of the other switches using analog trunks.

                In fact I have specifically tried this on the SGT1k switch and not had the problem, likewise I cannot reporduce the problem on using analog trunks.


                • #9
                  Were you ever able to resolve this issue? We are experiencing the same issue. We have verified it is not cabling, music source, or interference.

                  It appears to meet the same criteria.

                  1. Only happens on calls going over SG T1 switch
                  2. Only happens when person on hold makes a sound. If the person listening to MOH mutes their phone the distortion goes away.
                  3. Does not happen on analog trunks


                  • #10
                    I did not ever get this resolved. Now we are using centralized trunking, and I don't think I ever considered MoH at the site where our trunks are until now. So I don't even know what the status is. The silence on hold has always worked pretty reliably though.


                    • #11
                      I think the best way to describe this cable and the mini connector is to say that a mono connector has 1 color band on the tip, a stereo tip has 2 bands


                      • #12
                        The output of your music-on-hold device must be no more than 1 volt peak-to-peak (0 dBu) and must use a mono cable and not an unbalanced stereo cable (wherein, when connecting it to the Shoretel unit, the two stereo channels are essentially shorted together to make a mono signal). Many times, this will require you to turn the volume on the MoH source down as far as it will go.
                        We ran into an issue with MoH where distortion was getting introduced due to the piece-of-junk AC-DC power adapter used for the MoH source in conjunction with a poorly-grounded AC outlet. We called in the electricians to properly ground the outlet and we replaced the junk power adapter with a full-wave rectified power adapter (a true DC supply) and the noise went away. It does help to insure both the Shortel equipment and the MoH equipment are on the same power phase and the same ground plain.


                        • #13
                          I had this same issue, got a device specifically for music on hold where you load the songs onto a USB Thumb drive.

                          Problem solved


                          • #14
                            Originally posted by METRO25 View Post
                            I had this same issue, got a device specifically for music on hold where you load the songs onto a USB Thumb drive.

                            Problem solved
                            What device did you use? I am having similar issues with our MOH.
                            Music supplied from a computer (through Windows Media Player) is distored and unusable.


                            • #15
                              I've tried an android mp3 player and an Intellitouch OHP 8000 USB On-Hold Player. The android device had a stereo cable and the Intellitouch has a mono cable. Both sounded fine when calling in from a land line. However, the on hold music is really choppy from a cell phone. We have an SG220t1 switch.