Incoming sound in calls intermittent, outgoing fine

Discussion in '3CX Phone System - General' started by luisalonsoramos, Aug 31, 2011.

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  1. luisalonsoramos

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    Hello,

    I just went live with my 3CX setup yesterday, and although it seemed to work fine, I've had some problems today.

    Basically I hear the other party (external) intermittently, while they say they hear me perfectly. Internal calls (from extension to extension) are heard perfectly.

    My setup is as follows:

    * 3CX's PSTN lines are actually extensions in an analog Panasonic PBX, but that worked fine during tests and yesterday.
    * 3CX server is inside a LAN, where all the softphones are (there is one remote softphone -- it worked yesterday and I have not tested it today). It's a physical machine running Windows 2008 R2.
    * I am using a Grandstream GXW-4104 gateway

    Any ideas? Thanks in advance.
     
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  2. luisalonsoramos

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    Thanks for the spam. I am sure it will help me and other forum visitors solve our problems. :S
     
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  3. nbailey

    nbailey Member

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    Didn't you hear? a little bit of spam goes a long way in the troubleshooting department.

    :)
     
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  4. willow

    willow Member

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    I would put a butt set on the analog line and monitor the call and see where the audio us dropping. You may have a bad port or something like that on the grand stream..
     
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  5. luisalonsoramos

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    What is a butt set?

    The lines used to be connected to regular phones and they worked fine. So I suppose it's something on the setup. Could it be something on the network? But it's strange that problems are only one way.

    Thanks.
     
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  6. leejor

    leejor Well-Known Member

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    It's a telephone "persons' test set with alligator clips on the end of a cord for testing phone lines, also known as a butt-in.

    Is it quick drop outs, or long (1 or 2 second) silences? Being one way I would suspect the Grandsteam (settings?) or your network. You don't happen run through a Hub (as opposed to a switch) do you?

    It may not be an issue, but, some PBX's only supply 24 volts (rather than 48) to handsets (line idle state). That can make a difference in how an ATA interprets whether the line is in use. You would have to check your PBX to see if this will be a problem. there is probably a setting in the Grandstream to account for different voltages, that you may want to change, if you haven't already.
     
  7. luisalonsoramos

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    Quick, probably less than a second, but often enough to make understanding the other party difficult. I am using a switch.

    If it were the Panasonic PBX, it would happen always, right? This problem didn't happen the first day but yestarday was so bad, and today slightly better but still bad enough.

    Thanks!
     
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  8. eagle2

    eagle2 Well-Known Member

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    Check the line voltage of Panasonic port - it is typically 29V.
    Some gateways (like Cisco/Linksys SPA-3102) expect minimum 30V, otherwise unpredictable effects happen, as the line voltage is fluctuating and the SPA-3102 considers it as either line in-use or second phone having picked the line simultaneously, hanging-up does not disconnect the line, etc. However you may adjust this parameter in SPA-3102 (I usually set it to 18V), which solves all issues (Panasonic line-in-use voltage is 6 - 7 V). Port impedance setting in SPA-3102 is also related.

    I had similar symptoms with GXW-4104 and Panasonic PBX, so I assume the problem is similar. I didn't had the time to play with GXW-4104, but with default settings it is NOT working satisfactory when attached to Panasonic extension lines.

    Regards
     
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  9. luisalonsoramos

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    Thanks for your comments, Orlin. I don't think the GXW-4104 has the option to change the line voltage. I've searched everywhere and didn't find something like that.

    I tried testing with a SPA-3102, but I never got it working right. One big problem it has is that I cannot set any subnet mask (are only limited to /24 and higher) and for my network I need /21.

    I was trying the SPA-3102 and got it to register with 3CX, but never to answer the phone lines. In the meantime I got the Grandstream to work (almost) and abandoned the SPA-3102.

    I'll have to keep trying things around.

    Thanks!
     
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  10. willow

    willow Member

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    can you run wireshark captures on the grandstream device. if it is a second or two it may be network issues with qos. Is qos enabled on the network? if you are running captures on the network you should be able to see the rtp packets and find if they are being dropped or what.
     
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  11. luisalonsoramos

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    Thanks, Willow. I will try that and let you know of any findings.
     
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  12. eagle2

    eagle2 Well-Known Member

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    Unless you are using some old or customized firmware, there is no limitation in mask you want to use. I just tried and address like 192.168.0.10, mask 255.255.240.0 (which is /20) and gateway 192.168.0.1 and it works normally.
    My SPA-3102 has firmware version 5.1.7 (GW) - which I believe is the latest. Hardware version 1.1.5. I have installed over a hundred SPA devices with various PBXs.

    3CX is working more than perfect with SPA-3102. It is something you haven't set correctly or you are experienced voltage line-in-use problems.

    Regards
     
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