How ADSL with ISDN line works

[maestro_mihagi]

Hi, I am new to the forum so I hope I am posting in the right section.
I was wondering if you can help me to understand how the internet connection/landline system works in my girlfriend's place in Patras. I wanted to help her to add an extra phone on the line but I did not manage.

She has an old ISDN line at home, her provider is OTE. from the plug on the wall I can see TWO separate phone wires connected to a grey box. One cable goes directly to the box, the second one has a ISDN filter. The box has USB and serial port and some LED for "LINK" "B1" B2" options.
The output of this box is a single cable that enters a splitter. From the splitter one cable goes to the phone, one to the router (SAGEM 2444, Annex B).

-Why there are two phone cables coming out of the phone plug? Does she have 2 separate lines for phone and internet?
-What is this grey box used for?
-Do you think she can ask the provider for a new phone line to have internet and phone together and get rid of the old isdn line?


ευχαριστώ πολύ

[kage]

photos will be better...
153903
netmode isdn box used when u want to talk simultaneously(using only 1 phone number) from 2 telephone devices or fax machine linked to b1 b2 port

[maestro_mihagi]

photos will be better...


Hi kage, thank you for your reply. Yes, that's exactly what I was talking about. Now I understand better.
From the picture it seems that you can get ADSL from the ISDN line, is it correct? Also, if I remove the ISDN box and connect directly the phone to the splitter it will work, right? Thanks

[netblues]

Hi kage, thank you for your reply. Yes, that's exactly what I was talking about. Now I understand better.
From the picture it seems that you can get ADSL from the ISDN line, is it correct? Also, if I remove the ISDN box and connect directly the phone to the splitter it will work, right? Thanks

No.. It won't. ISDN offes two concurrent voice lines at b1, b2 and works like a modem over the line.
You can add as many phones as you wish in parallel, connected either at b1 or b2 analog ports.

[jkoukos]

From the picture it seems that you can get ADSL from the ISDN line, is it correct?
xDSL (ADSL or VDSL) can be over either POTS (PSTN) or ISDN telephony system.
In both cases a splitter is needed to separate xDSL High Frequencies from telephone Low Frequencies.


Also, if I remove the ISDN box and connect directly the phone to the splitter it will work, right?
No, it won't work. On ISDN system, a terminal adapter (NT) is needed to provide voice communication.
Consider this adapter as a modem which has 2 B channels and one D channel respectively for voice and data (signaling and control) communications.

On POTS system, there is no need for NT adapter, therefore you get voice communication directly from splitter.

[maestro_mihagi]

No.. It won't. ISDN offes two concurrent voice lines at b1, b2 and works like a modem over the line.
You can add as many phones as you wish in parallel, connected either at b1 or b2 analog ports.



No, it won't work. On ISDN system, a terminal adapter (NT) is needed to provide voice communication.
Consider this adapter as a modem which has 2 B channels and one D channel respectively for voice and data (signaling and control) communications.


Thank you very much guys, I think I got it now. I attached a scheme of how I think the connection is made.
153916

I am not sure if the router is connected from the ISDN filter or after the (NT) but I will check next time.
When I tried to connect an extra phone on the ground floor I could hear only noise. Since I didn't have a filter, I disconnected the filter connected to the (NT) and everything stopped working. I did not realise that the main plug is B1!
Thank you all for your help, you are amazing. :worthy:

[jkoukos]

According to your sketch, wiring should be:
153922

PS: A better sketch:
153923

[maestro_mihagi]

Thanks jkoukos. You are right about the router connection, but I am sure there are 2 separate cables coming out from the main plug (plug 1 in my very bad sketch). This configuration is realised on second floor. There is a phone connected in parallel with the main phone in the sketch and working properly on ground floor. If I understood correctly, the only way for it to work is to be connected to the B1 port of NT, right?

[jkoukos]

Yes, the only way for 2 phones to work is to be connected to the B port(s) of NT.
Probably the 2nd cable (that is coming out from the main plug), is not connected anywhere and the phone on ground floor is connected parallel on NT's B port.