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Technology Stocks : How high will Microsoft fly? -- Ignore unavailable to you. Want to Upgrade?

To: The Duke of URL© who wrote (56993)	4/1/2001 1:18:55 PM
From: Wayne Rumball	Read Replies (1) \| Respond to of 74651

Has anyone confirmed this? Message 15595191

To: The Duke of URL© who wrote (56993)	4/1/2001 1:56:01 PM
From: dybdahl	Respond to of 74651

Not exactly. ISDN is a digital telephone system. Created in the 1970's, it became widely used in the 1990's and in some countries it was covering 100% of the geographical area in 1996. It works like ADSL - only one pair of copper wire, on which there are three channels: 2 B channels with 64kbps on each 1 D channel with 16kbps packet switched data You can also get bigger ISDN connections, but this one is what most home users have. The D channels is normally only used for call negotiation etc. In Europe, we use the B channels as they are, but in the U.S., you add some extra overhead, reducing the bandwidth to 56kbps per channel. But since 56kbps corresponds to 6,5kbyte/sec, it's still better than a 56kbps analog modem, that can at most achieve 5,6kbyte/sec, because it transmits 10bits/byte. A telephone conversation only uses one B channel, so that you can use your phone and be on the internet at the same time. In Europe, HTTP/FTP download speeds on ISDN are 7,6kbyte/sec with one B channel and 15,5kbyte/sec with two B channels (approx.). By using "Bandwidth on demand", two channels are allocated when necessary, but not always. Bit Error Rate must be below 1E-9. There are many protocols for using several B channels for the same internet connection, and it works quite well. In Europe, one ISDN-2 connection with 2 B channels can have up to 8 telephone numbers. You just assign one of these 8 numbers to an "analog port" on your ISDN modem or router, and this analog port will then receive calls on that number. ISDN is very well-suited for families with children, and costs about the same as an analog line in monthly fee and exactly the same per minute. ISDN is not restricted to any geographical area - telcos must supply ISDN anywhere. Ameritech has a product here in Denmark that combines ISDN and ADSL. If a customer should be one of the few that cannot get ADSL, they can get flatrate ISDN 128kbps (15,5kbyte/sec in both directions) internet access for about $40 a month. Not good, but okay. Ping-delay through an 128kbps is typically 30ms, which is quite good compared to my 1Mbps Ameritech ADSL, that has a ping delay of 20ms. (My secondary 512kbps line from WorldOnline only has 7ms) Lars.