Can a modem dial ISDN?

[Jibber]

A simple question I hope:

Can a modem (for example,a 56k PC Card) dial-in to a PRI ISDN card? If so, are there any caveats such as the loss of multiple connections etc.?

I don't understand how a device that creates an analogue signal can connect to a digital device like ISDN, but I am being told by a 'superior' that this is possible.

Many Thanks

Jibber.








==

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[jeter]

I would say no, because of the isdn switch at the central office. If your boss says its possible tell him/her to give you and example. Jeter@LasVegas.com
J.Fisher CCNA

 

[Guest_imported]

Jibber...to keep it simple a "PC" card would need to support ISDN. For example a ISDN/BRI (128k) interface requires a terminal adapter which most home PC users use to connect via ISDN/BRI. For ISDN/PRI, which is physcially a t1 digital ckt connected to an ISDN switch at the telco provider and a ISDN/PRI interface card at the customer site.

 

[Jibber]

Thanks for the information, I have yet to get any from my own colleagues!

So, tell me if I have this right; if we have a router with a PRI card, the ISDN line is between this device and our provider's PABX. Would it then be possible to dial one of the numbers provided for that line using a modem, and have the provider deal with the conversion?

I have also made a discovery regarding the router. According to it's configuration it has digital modems installed. Each of these seems to be connected to the ISDN card via ribbon cable, and neither has an interface for a phone cable. This suggests to me that the card arrangement is smart enough to sense the type of connection required at the time of a call and deal with it as necessary. Does that sound likely to anyone?

Jibber








==

Ask me your Win95 and DHCP questions:

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[workaholic24x7]

Jibber...What are you trying to establish with the ISDN PRI Card in the router?? Typically the Card could handle the PRI/ISDN line (24b and 1 D channel). You would have to establish the same D channel protocol between you and your provider's ISDN switch (ie. 5ESS or DMS250, etc).... Are you also trying to do outbound or inbound calling on this ISDN line?

 

[Jibber]

I was trying to implement dial-up using an ISDN adapter, to a Shiva LanRover. We have quite a few ISDN2 lines available for this. I think I have all the necessary kit, but I am seriously lacking in ISDN experience! We have recently abandoned the Shiva after I raised the issue that they are not supported. Now I need a new solution . . .
==

Ask me your Win95 and DHCP questions:

Jamie.Clay@bigfoot.com

 

[ronr101]

In answer to your question, can a modem dial into an ISDN PRI... it depends. There are some PRI devices on the market that support analog calls. I have used a card from Eicon Networks that can do this. They make a PRI card that is designed to be installed in an NT server and to use RAS and receive calls from both ISDN devices and regular modems (56k).

 

[MaxPipeline]

>Can a modem (for example,a 56k PC Card) dial-in to a PRI >ISDN card? If so, are there any caveats such as the loss >of multiple connections etc.?
>
>I don't understand how a device that creates an analogue >signal can connect to a digital device like ISDN, but I am >being told by a 'superior' that this is possible.

Jibber,

Assuming that your PRI is provisioned to handle analog calls this is possible and actually common. The PRI uses the D-channel to carry the bearer information which tells your RAS what type of call is incoming. If the call is digital (ISDN BRI) then the call should get routed to an HDLC driver. If the call is analog then it should route to a modem.

Now your RAS needs to have modems installed in order to answer the analog call which your device seems to have. The ISDN provider does not deal with the line conversion per se. Your RAS actually has the task of determining how to route the incoming call. The data is digital either way. Your digital modem actually converts it back to analog. Again this information is carried in the D-channel.

The caveat is that you are not using the full 64k bandwidth which can be waistful. But this is an acceptable loss to most. The most you will ever be able to utilize for analog is 56k whereas with an ISDN BRI caller you can get the full 64K per channel.

BTW for clarification, a PRI is 23 64k b-channels and 1 64k d- channel, not 24 b channels. The 23 channels plus the D make up the full 24 DS0's of a PRI.

>I have also made a discovery regarding the router. >According to it's configuration it has digital modems >installed. Each of these seems to be connected to the ISDN >card via ribbon cable, and neither has an interface for a >phone cable. This suggests to me that the card arrangement >is smart enough to sense the type of connection required >at the time of a call and deal with it as necessary. Does >that sound likely to anyone?

In a word, yes the card should recognize the proper protocol based on the d-channel information. Your digital modem can probably act as an HDLC driver as well as an analog modem.

I hope this answers your questions
-Rich

 

[PaulG4AWZ]

jibber the answer is yes
I have 4 different devices here, 2 are standalone
and 2 are PC cards, the 2 standalone boxes are connected to a BRI ISDN incoming line,they have 2x 25way RS232 connectors which go to 2 PC'S com ports, also two RJ11
BT telephone sockets one is configured for a FAX machine
and the other is an ordinary POTS DTMF telephone
this has a splitter to another PC that has a 56k FAX modem for backup purposes,the in/out analog conversion is done in the ISDN Terminal Adaptor BOX.you can only use 2 of the 4 ports concurrently. as the bandwidth is only 128k.....
The other 2 cards have only one telephone connection
and fit inside a PC with the data link direct to the bus.