Need an ISDN modem

[DGath]

Need to find an ISDN modem for a client and their service is through Sprint. Apparently Sprint told them they just have to find one on their own, as they don't sell or rent them. Weird. Anyways... I know nothing about how picky or standardized ISDN service is, does it matter what modem they get or just any modem out there?

Thanks.

 

[DGath]

Searched around in hardware and networking prior to this thread, and couldn't find any info. However, managed to find this in off-topic of all places, and it answered most of my questions. So basically EBay is the best place to get these things becuase I'm looking through all of my hardware vendors and can't find anything reasonably priced.

 

[timernstes]

I have a spare Cisco 804 series ISDN modem/router if you happen to still be looking for one.

 

[ScottMac]

Ther's no such thing as an ISDN modem; I believe you're looking for a terminal Adapter (TA).

You'll want to make sure you get the right ISDN interface. TO connect directly from the jack to the TA / router, you need a "U" interface on the device.

If you have several devices to connect to the same jack, you'll need 1.) an NT1 (a "U" interface on one side, one or more "ST" interfaces on the other)... and 2.) "ST" interfaces on all of the devices.

If you plug a "U" device into an NT1, smoke happens and the devices stops working.

(Same for plugging ST devices directly into the network jack)


USR used to produce an "I-Modem" which was a TA and analog modem in the same modem-looking device.

Also keep in mind that many / most / all external TAs are limited to 115KBaud, even though the ISDN line has 128K of bandwidth (when using MLPPP). Internal TAs usually operate at the full 128K (if the channels are multi-linked).

Also be aware that some of the older TAs (Like an Adtran ISU128) REQUIRES the use of SPIDs, and so will not work with most 5ESS Custom configured networks (5ESS Custom service does not have SPIDS).

Good Luck

Scott