[Asterisk-Users] PSTN Incoming call on real line disrupts VoIP call over DSL circuit - EXPLAINED

[Bob Chiodini]

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.


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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