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  • 1.  Top 10 reason calls disconnect from a Network Engineer point of view....

    Level 1 Contributor
    Posted 09-30-2021 07:21

    The term disconnect here is defined as you are talking on an active call (aka you have not put it on hold, parked, in the process of picking up, etc) and the call ends. You no longer see the call on your display with the call timer incrementing. If you do see the call on your display with the timer incrementing, that means the call is still continuing and has lost audio, which is a different topic (but maybe related).


     The below top ten are listed in order. Always refer to 8x8's Network Requirements document https://support.8x8.com/cloud-phone-service/voice/network-setup-voice/x-series-technical-requirements for best practices. This covers both UC (Work) and CC (VCC) Calls.


    1. The Public IP has changed 
      1. FIX: usually related to Multi-path, load balancing, failover, redundancy actions of a router with 2 or more WAN ports or a SDWAN device.
    2. The NAT Port changed
      1. FIX: TCP timer is less than 300 - 700 seconds (TLS connections only, port 5443)
      2. FIX: UDP timer is less than 300 seconds
      3. FIX: Ensure all devices have a unique NAT Assignment (for example each device has a unique IP:Port combination)
      4. General NAT assignment/session issue with edge
      5. When making corrections to timers make sure you apply to ALL layer 2 or 3 devices as some networks may have multiple firewalls, access points in line.
    3. The device has lost registration with 8x8
      1. FIX: See 1 and 2 
    4. SIP Signalling is blocked such as Keep-Alive/ACK communication or Session Timers are interrupted
      1. FIX: Ensure over protective Security practices are not causing the issue such as DPI, SSL Decryption etc.
    5. Incorrect Call Control
      1. FIX: attempting to use the call control (park, hold, transfer etc) from your Physical device or the Work Application, call control must be done from the Contact Center Agent Interface. VCC should be set up where Work applications do not present call control features.
      2. FIX: WorkD is set to Call Using Deskphone, but attempt to use Call Control in WorkD, always use the call control of the device in this situation.
    6. Remote side disconnected unexpectedly
      1. Cellular drops due to Poor coverage (tunnels, building restrictions, network overload)
    7. Wireless Headset disconnects
      1. FIX: Check battery
      2. FIX: Check within range
      3. FIX: Update Firmware of device or OS
    8. Loss of Internet
      1. FIX: Check internet connection
      2. FIX: Check WiFi Status if using WiFi (SEE: https://support.8x8.com/equipment-devices/network-devices/SoHo_Networking_Design_Best_Practices )
    9. Loss of Power
      1. FIX: Restore Power
    10. Carrier Issue
      1. 8x8's NOC will manage this situation and release an outage notification (See: https://status.8x8.com/#!/


    When reporting issues to 8x8 support the following information is KEY to assisting 8x8 in identifying the cause of the call drop. It is CRITICAL to report as soon as you can due to the length of time logs are available.


    • If you have an open ticket provide the ticket number, or reference that there was an open ticket for this previously
    • What was the exact representation/experience when this happened
      • Example: I was on the call for 1 min talking and then the call dropped, caller called back and said they could not hear me.
      • Example: I was on the call for 45 seconds and then could not hear anything, eventually the call ended.
      • Example: Call was very choppy, very hard to understand, audio cutting in and out and then it was gone.
    • Were you on a hard phone, Work for desktop, or Work for Mobile
    • Were you In the office, at home, or "on the road"
    • Do you have more than 1 WAN link?
      • If yes, how is load balancing, load sharing, failover, SDWAN implemented?
    • Were you on WiFi or Hard Wired?
    • What was the time & date of the call along with the Caller ID (Inbound) or Number Dialed (Outbound) as well as your extension number
    • Approximately how many times has this happened to you previously, and does it happen to others in the organization

    It is important to note that the Network Utility or Network Assessment tool will provide little to no assistance in resolving this issue due to the tool is designed to identify issues in Setting up a call or registration issues not identifying issues of an ongoing call. Nor will the MOS score of the call/past calls in most cases, thas MOS is related to the RTP stream also known as "Voice Quality" For example the call was choppy. This information is always welcomed but may yield little help.



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    Paul Chase
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  • 2.  RE: Top 10 reason calls disconnect from a Network Engineer point of view....

    Posted 09-30-2021 08:05
    Excellent, valuable information Paul.    Two points in your list I'd like to comment on:

    2.5 "apply to ALL...."   - that's a good reminder.  We often get hyper-focused on the Router or Firewall appliance and forget that further inside our LAN could be other devices with timers of their own!

    9.1 "Loss of Power".   In heavy industrial settings, power can have very short "blips" of power loss (or dips).   Introducing a UPS (Uninterruptible Power Supply) device to the Modem, Router, firewall, and PoE switch would be a great way to protect from this problem.   

    Thanks for adding that information, Paul  :-)

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    Steve O'Neal
    Sr. Deployment Engineer
    8x8 Center of Excellence
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  • 3.  RE: Top 10 reason calls disconnect from a Network Engineer point of view....

    Level 1 Contributor
    Posted 09-30-2021 22:56

    Tons of gems in this post @Paul Chase . This is saved and something I'll come back to for reference.

    Great points too on providing as much detail as possible when working with support. 

    Thanks for sharing. 



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    Jahmal Abbott
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  • 4.  RE: Top 10 reason calls disconnect from a Network Engineer point of view....

    Posted 11-02-2021 14:54

    Thank you again, @Paul Chase, both for the above and for helping to make this invaluable ​knowledge available on the 8x8 Support KB: https://support.8x8.com/cloud-phone-service/voice/network-setup-voice/Top_10_Reasons_Calls_May_Disconnect

    Nicely done!!



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    Joel, 8x8 Global Customer Care
    (he/him/his)
    Minneapolis
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