Re: Problem with VOIP adaptor + Localphone.com + Internet Via Satellite

Discussion in 'UK VOIP' started by David Woolley, Mar 15, 2013.

  1. Anti-Spam wrote:
    > I am having problems setting up a Handytone HT502 with Localphone.com.
    > The internet connection is coming in, via Internet Via Satellite, with
    > a small amount of Latency, if thats relevant?


    If this uses geosynchronous satellites, you won't get less than medium
    latency.
    >
    > Also, if its relevant? the grandstream is set to NAT router mode for
    > the Access Point (Edimax) which follows it.


    The risk here is that it also munging the SIP headers.
    >
    >
    > 1. On any incoming call on the VOIP system, the POT handset rings
    > about 2 times. If you manage to pick the phone up, before the end of
    > the two rings, then you can use the phone as normal with no problems
    > (we are aware of). If you do not pick up within the two rings, the
    > phone stops ringing and the caller stops hearing a ringing tone, and
    > gets an unobtainable tone.


    This sounds as though interim responses are not getting through. That
    is weird. Also, I don't think a normal SIP system should abort the call
    after that short a time without a response. Does the caller get
    ringback tone when the adapter is powered down. That would indicate
    that the ringback is being generated before the network has had
    confirmation of ringing. If you get immediate unobtainable, this test
    may not be valid, because a non-SIP mechanism is actively reporting the
    loss of connection.

    >
    > 2. When making outgoing calls on the VOIP system, the phone works as
    > it should only if the person called, picks the phone up. But if the
    > person called, does not pick up, and the caller puts the handset down,
    > it does not stop the phone ringing at the person called end (we have


    That indicates a problem with CANCEL. There can be issues with the
    adaptor or the central system failing to include tags, or insisting on
    them when the protocol doesn't actually require them.

    Ideally you need a packet capture and a trace of the SIP protocol, to
    see what is happening.

    > only tried this with a mobile). If you pick up the VOIP phone, it now
    > gives the dial tone (even though the called persons phone is still
    > ring) eventually the called persons phone, times out and stops
    > ringing.


    Dialtone will be generated by the adaptor without talking to the
    network. The adaptor can safely return it immediately, as it can start a
    new SIP call whilst still retrying the CANCEL on the old one.
    >
    > These TRAC phones,
    > as they are called, are charged at normal landline phone call rates.
    > We have found (by accident) that if the VOIP phone is rung by a TRAC
    > system phone, the message comes back to the caller that the number is
    > unobtainable, we tried it on two different TRAC phones and got the
    > same result.


    This sounds like it is due to commercial, rather than purely technical,
    issues.
     
    David Woolley, Mar 15, 2013
    #1
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  2. David Woolley

    Dave Saville Guest

    On Fri, 15 Mar 2013 11:07:35 UTC, M & S <> wrote:

    > Grandstream HT502 set to NAT issuing DHCP IP addresses (in a different
    > subnet) to a Edimax Access point. I presumed that the VOIP traffic
    > would be processed before the NAT router section, in which case do we
    > need to do something with NAT traversal? or do you not mean this?


    Yes you do. If any SIP device is behind NAT then you need either:
    A SIP ALG in the router - Usually buggy.
    Use a STUN server
    Use a Proxy server

    The problem is that the SIP protocol puts the device address *inside*
    the packets so "normal" NAT does not see/change them. You get outgoing
    but no incomming as the other end does not know where to send the
    response.

    HTH
    --
    Regards
    Dave Saville
     
    Dave Saville, Mar 15, 2013
    #2
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  3. David Woolley

    Graham. Guest

    On Fri, 15 Mar 2013 20:02:49 +0000, alexd <>
    wrote:

    >Dave Saville (for it is he) wrote:
    >
    >> Yes you do. If any SIP device is behind NAT then you need either:
    >> A SIP ALG in the router - Usually buggy.
    >> Use a STUN server

    >
    >Surely ITSPs have got workarounds for this by now - all they need to do is
    >reply to the source IP address rather than what's in the SIP headers?
    >
    >> Use a Proxy server

    >
    >I think most people fall into this category. Set their SIP device to use
    >their ITSPs server as their SIP proxy.


    Can you explain the alternatives and their advantages?

    --
    Graham.

    %Profound_observation%
     
    Graham., Mar 15, 2013
    #3
  4. David Woolley

    Dave Saville Guest

    On Sun, 17 Mar 2013 20:22:24 UTC, Anti-Spam <> wrote:

    > On Fri, 15 Mar 2013 13:29:51 +0000 (UTC), "Dave Saville"
    > <> wrote:
    >
    > >On Fri, 15 Mar 2013 11:07:35 UTC, M & S <> wrote:
    > >
    > >> Grandstream HT502 set to NAT issuing DHCP IP addresses (in a different
    > >> subnet) to a Edimax Access point. I presumed that the VOIP traffic
    > >> would be processed before the NAT router section, in which case do we
    > >> need to do something with NAT traversal? or do you not mean this?

    > >
    > >Yes you do. If any SIP device is behind NAT then you need either:
    > >A SIP ALG in the router - Usually buggy.
    > >Use a STUN server
    > >Use a Proxy server
    > >
    > >The problem is that the SIP protocol puts the device address *inside*
    > >the packets so "normal" NAT does not see/change them. You get outgoing
    > >but no incomming as the other end does not know where to send the
    > >response.
    > >
    > >HTH

    >
    > You are way above my understanding of these matters, but for arguments
    > sake, just so we are clear. My system is Satellite Internet Modem,
    > feeds Grandstream HT502 (Incorporating NAT), (WAN side on DHCP talking
    > to Satellite internet modem) (LAN side on different Subnet, talking to
    > a Belkin Internet Access Point) I assumed that the VOIP section of the
    > VOIP adapter, would be on the WAN side of things, so not affected by
    > the NAT, or am I being a Twat?


    So: nasty internet -> modem - DHCP> HT502 -NAT> Access point

    So where is the VOIP adaptor?
    --
    Regards
    Dave Saville
     
    Dave Saville, Mar 18, 2013
    #4
  5. On Mon, 18 Mar 2013 13:01:25 +0000 (UTC), "Dave Saville"
    <> wrote:

    > On Sun, 17 Mar 2013 20:22:24 UTC, Anti-Spam <> wrote:
    >
    >> On Fri, 15 Mar 2013 13:29:51 +0000 (UTC), "Dave Saville"
    >> <> wrote:
    >>
    >>> On Fri, 15 Mar 2013 11:07:35 UTC, M & S <> wrote:
    >>>
    >>>> Grandstream HT502 set to NAT issuing DHCP IP addresses (in a different
    >>>> subnet) to a Edimax Access point. I presumed that the VOIP traffic
    >>>> would be processed before the NAT router section, in which case do we
    >>>> need to do something with NAT traversal? or do you not mean this?
    >>>
    >>> Yes you do. If any SIP device is behind NAT then you need either:
    >>> A SIP ALG in the router - Usually buggy.
    >>> Use a STUN server
    >>> Use a Proxy server
    >>>
    >>> The problem is that the SIP protocol puts the device address *inside*
    >>> the packets so "normal" NAT does not see/change them. You get outgoing
    >>> but no incomming as the other end does not know where to send the
    >>> response.
    >>>
    >>> HTH

    >>
    >> You are way above my understanding of these matters, but for arguments
    >> sake, just so we are clear. My system is Satellite Internet Modem,
    >> feeds Grandstream HT502 (Incorporating NAT), (WAN side on DHCP talking
    >> to Satellite internet modem) (LAN side on different Subnet, talking to
    >> a Belkin Internet Access Point) I assumed that the VOIP section of the
    >> VOIP adapter, would be on the WAN side of things, so not affected by
    >> the NAT, or am I being a Twat?

    >
    > So: nasty internet -> modem - DHCP> HT502 -NAT> Access point
    >
    > So where is the VOIP adaptor?


    http://www.grandstream.com/index.ph...hony/consumer-analog-telephone-adaptors/ht502
     
    Anthony R. Gold, Mar 18, 2013
    #5
  6. David Woolley

    Dave Saville Guest

    On Mon, 18 Mar 2013 13:23:38 UTC, "Anthony R. Gold"
    <> wrote:

    > On Mon, 18 Mar 2013 13:01:25 +0000 (UTC), "Dave Saville"
    > <> wrote:
    >
    > > On Sun, 17 Mar 2013 20:22:24 UTC, Anti-Spam <> wrote:
    > >
    > >> On Fri, 15 Mar 2013 13:29:51 +0000 (UTC), "Dave Saville"
    > >> <> wrote:
    > >>
    > >>> On Fri, 15 Mar 2013 11:07:35 UTC, M & S <> wrote:
    > >>>
    > >>>> Grandstream HT502 set to NAT issuing DHCP IP addresses (in a different
    > >>>> subnet) to a Edimax Access point. I presumed that the VOIP traffic
    > >>>> would be processed before the NAT router section, in which case do we
    > >>>> need to do something with NAT traversal? or do you not mean this?
    > >>>
    > >>> Yes you do. If any SIP device is behind NAT then you need either:
    > >>> A SIP ALG in the router - Usually buggy.
    > >>> Use a STUN server
    > >>> Use a Proxy server
    > >>>
    > >>> The problem is that the SIP protocol puts the device address *inside*
    > >>> the packets so "normal" NAT does not see/change them. You get outgoing
    > >>> but no incomming as the other end does not know where to send the
    > >>> response.
    > >>>
    > >>> HTH
    > >>
    > >> You are way above my understanding of these matters, but for arguments
    > >> sake, just so we are clear. My system is Satellite Internet Modem,
    > >> feeds Grandstream HT502 (Incorporating NAT), (WAN side on DHCP talking
    > >> to Satellite internet modem) (LAN side on different Subnet, talking to
    > >> a Belkin Internet Access Point) I assumed that the VOIP section of the
    > >> VOIP adapter, would be on the WAN side of things, so not affected by
    > >> the NAT, or am I being a Twat?

    > >
    > > So: nasty internet -> modem - DHCP> HT502 -NAT> Access point
    > >
    > > So where is the VOIP adaptor?

    >
    > http://www.grandstream.com/index.ph...hony/consumer-analog-telephone-adaptors/ht502


    Page 25 of the 502 manual gives the impression that VOIP is behind NAT
    --
    Regards
    Dave Saville
     
    Dave Saville, Mar 18, 2013
    #6
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