I don't think it's a NAT problem, as the only thing I change is my upstream routing. The Handset is connected via WIFI to my 4g hotspot it goes from not working to working just by changing the BGP Announcement. It's like one of the internet paths is dropping the traffic as rogue traffic because the other direction of the packet didn't flow through them.

I'm seeing the packet leave my network, it's just never getting to the destination until the inbound traffic is over the same provider.

On 12/3/2020 6:22 PM, Lewis Bergman wrote:
There is such a tool. There is a lower capability free version and a paid version. VoIPMonitor <https://www.voipmonitor.org/> Tough to say what might be going on. On the face it seems like the re invite doesn't know where to go as there is no NAT table connection entry from that port to the internal IP.

On Thu, Dec 3, 2020 at 6:13 PM Chuck McCown via AF <af@af.afmug.com <mailto:af@af.afmug.com>> wrote:

    I used to think SIP was OK.  I even helped GenBand (or whatever
    the Northern
    Telecom manufacturer was called after they were Northern Telecom )
    fix their
    SIP stack.  Took a ton of wire sharking and deep packet inspection
    but they
    had a fault.

    But I have forgotten everything I ever knew about SIP.  I am sure
    there is
    someone that makes a SIP tool the is like wire shark but decodes
    things into
    a much more easy to read format and then is able to launch SIP
    packets
    too... but too lazy to see if one exists.  A SIP simulator, or
    spoofer or
    stingray type of box.

    Needs to be made out of metal and have buttons, lights and meters
    on it.

    -----Original Message-----
    From: Ken Hohhof
    Sent: Thursday, December 3, 2020 4:57 PM
    To: 'AnimalFarm Microwave Users Group'
    Subject: Re: [AFMUG] Offnet SIP and Multi-homing

    I thought re-invites were used to get the media stream to flow
    directly
    between the endpoints and bypass the PBX.

    And if you took out the asymmetric routing, the other symptoms
    would make me
    think it's a NAT traversal or SIP ALG problem in the customer's
    router.  But
    with the dependency on how the traffic flows over the Internet, I
    haven't a
    clue.


    -----Original Message-----
    From: AF <af-boun...@af.afmug.com
    <mailto:af-boun...@af.afmug.com>> On Behalf Of Nate Burke
    Sent: Thursday, December 3, 2020 5:18 PM
    To: Animal Farm <af@af.afmug.com <mailto:af@af.afmug.com>>
    Subject: [AFMUG] Offnet SIP and Multi-homing

    I'm trying to track down a strange Issue I'm having, and wondering
    if anyone
    has run into something similar.

    I have a couple customers that I let take phone handsets home, the
    Grandstream PBX is at our office.  It seems that if the SIP
    traffic comes in
    one upstream, but leaves another upstream, really weird things happen.

    The Phone registers to the PBX just fine, and can receive calls
    all day
    long, it just cannot make calls.  If I take a /24 and force it to
    enter and
    leave the network via the same provider, then everything works
    fine.  Those
    of you that have multiple diverse paths, have you seen something
    like this?
    The Call in UDP Mode fails, the call in TCP mode will succeed.

    This only appears to be an issue with the handset talking to the PBX.
All of our Sip Trunk traffic (Voip Innovations) works just fine. For some
    reason the handset SIP re-invite never makes it back to the
    handset when
    multi-homing is in place.



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--
Lewis Bergman
325-439-0533 Cell



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