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  • Inter-Site drops when sent to voicemail

    We have an SG90 switch at our headquarters and an SG50 at a remote site which is connected via a VPN over a low-quality internet connection.

    When a call is made from the remote site to headquarters and is left to ring through to voicemail, it is almost always dropped. You get to hear about one second of the greeting before being dropped back to a dial tone.

    If the recipient answers, the call does not drop. If the recipient pushes the call to voicemail without letting it ring out, it also does not drop.

    Calls from headquarters to the remote site do not seem to suffer from this problem.

    The poor internet connection does cause intermittent voice quality issues but they do not correlate at all to the dropped-call problem. If the recipient answers, the call is crystal clear. If the recipient does not answer, the call drops after one second of voicemail greeting.

  • #2
    What type of devices are terminating the VPN tunnels?

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    • #3
      The remote site is a Netgear FVS318. Headquarters is a Juniper Netscreen 5gt.
      No QoS has been implemented on either end (indeed, I don't think it's an option on the cheaper Netgear device). The connection carries very little collateral traffic - usually none.

      During good times we average 35 ms lag, 0.5% packet loss and 6.5 ms jitter.
      The worst test showed 155 ms lag, 2.4% loss and 7.5 ms jitter.

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      • #4
        I can't speak to the Netgear... Go turn off all of the ALGs on the Netscreen. If you have the option to do the same on the Netgear, you should.


        The ALGs will screw with Shoretel. Shoretel leverages SIP, MGCP and RPC but they aren't written to standards as they are Shoretel's own implementation.

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        • #5
          Thank you for your reply.

          Unfortunately, no ALGs have ever been enabled on the Netscreen device.

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          • #6
            This is a bit tougher without digging into the specifics of your config and tracing the call through the logs to see what is happening.

            You should certainly engage your Shoretel partner so they can troubleshoot this.

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            • #7
              Regarding the logs: is there anything more detailed than the Application and System logs available through the ShoreWare Director and Windows Event Viewer? They make no mention of these failures.

              Our ShoreTel partner is refusing to help. They feel that the poor connection between locations is to blame for any issue we may be experiencing. My position is that the issue is too isolated and consistent to be blamed on intermittent connection issues.

              I should note, our current partner did not engineer the installation - that company went out of business in the middle of the project.

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              • #8
                Yes, there are. Check the logs directory under Shoreline Data. The TMSNCC log will be a good place to start. It traces exactly everything that happens with a call as it flows through the system. You aren't going to have an easy time interepting this information though...

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                • #9
                  Vpn

                  No offense, but get some real VPN endpoints, and setup some limited QOS before you try and troubleshoot this problem.

                  You have a 75 dollar VPN endpoint.

                  Garbage in, Garbage out.

                  When you get to the point where you dont have any packet loss, then start troubleshooting.

                  I would recommend a matched set of VPN endpoints as well.

                  What are your upload speeds at both ends? Sounds like atleast one end is some sort of DSL with 512k up.

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                  • #10
                    I always love to tell people to implement the right equipment but sometimes that just wont happen.


                    The 5GT is just fine, ScreenOS is an amazing firewall. Although that product line is end of life.

                    You can pick up a couple of Juniper SSG5s if you want to stay with ScreenOS or pick up a couple of SRX100s if you want to move to Juniper's newer JunOS-based security platform.

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                    • #11
                      Originally posted by eazeaz View Post
                      No offense, but get some real VPN endpoints, and setup some limited QOS before you try and troubleshoot this problem.
                      None taken. I acknowledge that one of the endpoints is cheap. It was installed long before the ShoreTel system. I'm hoping to get a better understanding of the problem before I begin to throw money at it.

                      Originally posted by eazeaz View Post
                      When you get to the point where you dont have any packet loss, then start troubleshooting.
                      I don't think we'll ever achieve 0 packet loss but it is usually well below the 1% standard. This problem occurs in good times as well as bad.

                      Originally posted by eazeaz View Post
                      What are your upload speeds at both ends? Sounds like atleast one end is some sort of DSL with 512k up.
                      The final leg of the remote office's connection is over wireless. They're out in the sticks and it's wireless or satellite.

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                      • #12
                        I gather that it's the opinion of others that a questionable network connection may well be the cause of this specific drops-when-sent-to-voicemail problem. Even though it happens during times when tests show acceptable connection parameters and voice quality is solid?

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                        • #13
                          I am not sold that it is the cause, otherwise it would correlate. I'd bet on the VPN devices (more specifically the Netgear). The crappy Internet connection certainly does not help the case.

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