[Asterisk-Users] PSTN Incoming call on real line
disrupts VoIP call over DSL circuit - EXPLAINED
Juergen K. Zick
syscon-lists at ifa.uni-kassel.de
Wed May 10 01:44:22 MST 2006
Well,
>Bellsouth gave me a box of filters that have two RJ-11 jacks. One for
>the DSL modem and one for a phone. The instructions specified that
>every phone be connected to a filter. The DSL modem would then be
>connected to the DSL jack along with one of the phones. The modem
>should not be connected directly to a phone line.
>
>The point is to isolate (filter) the DSL signaling from the voice
>signaling as Juergen describes. However in the US the wiring is not,
>typically, "home-run", but daisy chained, one wall plate to the next
>with no place to put a whole house filter. Telcos do not like customers
>in the demark at the cable entrance and customers can install their own
>DSL equipment. I did. Bellsouth mailed the equipment to me with a CD
>and a set of paper instructions. It's just easier to tell the DIY'r to
>filter everything.
Yes, I was aware of that "daisy chain" problem. Nowadays, the same problems
are appearing in German flats as well, as many outlets / jacks are mounted
to the same line. And I agree that the TELCO advice for filtering
everything is much simplier for the DIY people, _BUT_ it can lead to a
mismatch of your phone line and additional reflections especially in the RF
band where the DSL signals are being located.
German phone jacks (TAE jacks) are different from RJ jacks and include
switches. That mean that you can install the splitter into the _FIRST_ TAE
jack connect your DSL modem to the splitter and the filtered POTS output
is automatically being sent into the the rest of the daisy chain ...
The proposed filtering works _ONLY_ when your line to the DSLAM is quite
short and you have not a high attenuation on it.
--Jürgen
But slowly, we are getting completely off-topic on this list. I doubt that
changing to static IP will solve to decribed problem, because it is a line
mismatch problem on the physical layer of the connection. And these will
not go away unless you change the wiring !
Hadar, I would suggest to try my wiring first before you take other action
to buy something. Also, while testing the line with BellSouth, I would ask
for BERT-tests in the ATM-layer loop of your DSL.connection while your
father has no phone talk on the POTS side and then with a running phone
talk on on his phone.
>Bob...
>
>
>
>
>
>On Tue, 2006-05-09 at 20:41 +0200, Juergen K. Zick wrote:
> > Well,
> >
> > to avoid a misunderstanding see the following drawing:
> >
> >
> >
> >
> /-------DSL-MODEM-----HT-----PC
> > H| |
> > +----------+
> Inet-PHONE
> > from BellSouth (DSL over POTS) ---| SPLITTER |
> > +----------+
> > L|
> >
> \------------------------------
> > |
> |
> > answering
> POTS
> > machine
> phone
> >
> >
> >
> > (maybe you have to reformat it into COURIER font)
> >
> > It's depending on the calling in your father`s flat but on the incoming
> > line you should have only _ONE_ device, the SPLITTER !!!
> >
> > maybe your dad can try that ...
> >
> > All DSL connections in Germany are build up like that and I have not seen
> > any that did _not_ work with this cabling ...
> >
> >
> > --Jürgen
> >
> >
> >
> >
> > >Juergen K. Zick wrote:
> > >>HI,
> > >>well, that was what I expected in my posting yesterday. For me, your
> > >>wiring looks strange. Here in Germany, we have "spiltters" connected to
> > >>the incoming line which have two outputs: A high pass filter output for
> > >>the DSL signal and a low pass output with DC pass-through for the POTS
> > >>signal. the DSL output is being connected to the DSL-modem and the POTS
> > >>output will feed your internal POTS wiring.
> > >
> > >The only jack that has both a phone and the DSL connector indeed has a
> > >splitter on it, provided by Bellsouth.
> > >
> > >>Therefore, there is _NO_ filter needed on each POTS outlet, because
> there
> > >>is nothing to be filtered out on your internal line anymore.
> > >
> > >You may be correct. I am definitely _not_ familiar enough with DSL.
> > >However, 5 years ago, I had a DSL line in my apartment, and I was
> > >specifically told by the installation tech that I needed a filter on
> _any_
> > >jack that had a real phone connected to it. That may not have been
> > >necessary, or perhaps isn't necessary any longer, or perhaps varies by
> > >provider, but that's what I was told at the time, and that's what I did
> > >(with no problems).
> > >
> > >The filters on the phone jacks that didn't have the modem connected were
> > >not splitters, just single filters.
> > >
> > >>Seen from my German wiring knowlegde, your cabling is wrong and causes
> > >>the interruptions on the DSL service.
> > >
> > >That's definitely possible, just not my personal (single point!)
> experience.
> > >
> > >>Don`t you have something like a "spiltter" available ? It should be the
> > >>_ONLY_ filter on your incoming line and then the DSL-modem and the POTS
> > >>phone should be connected to it ...
> > >
> > >OK, it would be easy for him to remove the other filters temporarily and
> > >test again.
> > >
> > >Thanks!
> > >
> > >>--Jürgen
> > >
> > >>>Replying to my own post (and my most recent follow-up). I have now
> > >>>confirmed 100% that the DSL modem gets a _new_ IP address every time
> his
> > >>>"real" phone gets answered, or hung up! This (of course) disrupts the
> > >>>audio coming from to him, since the sending machine (Asterisk in my
> > >>>case), no longer has the correct IP address to send to him.
> > >>>
> > >>>I lowered his registration from the default 1 hour to 1 minute, so
> after
> > >>>we're disconnected, I can see that he's re-registering with a new IP
> > >>>address, each and every time :-(.
> > >>>
> > >>>I told him to call Bellsouth and ask about a Static IP address, but I
> > >>>don't know if they offer it, or how much they charge.
> > >>>
> > >>>While this one isn't "solved", it's at least "explained".
> > >>>
> > >>>Thanks to everyone who responded!
> > >_______________________________________________
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