September 2001
Beginner
528 pages
14h 14m
English
Content preview from Essential Guide to Telecommunications, The, Third Edition
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
Appendix: Modem Standards
Tables 7.4 and 7.5 list Bell and ITU modem-speed standards. Standards have changed in two ways: Initially, they were set by the Bell system (AT&T). Now the International Telecommunications Union headquartered in Geneva, Switzerland, sets them. Standard modem speeds have increased from 300 bps to 56,000 bps.
| Standard | Modem Type | Speed (bps) | Fall-Back Speed | Comments |
|---|---|---|---|---|
| Bell 103 | Dialup | 300 | ||
| Bell 212 | Dialup | 1200 | ||
| Bell 208A | Leased | 4800 | ||
| Bell 208B | Dialup | 4800 | ||
| V.21 | Dialup | 300 | 300 | Used by Group 3 fax in half duplex mode for negotiation and control. |
| V.22 | Dialup, leased | 1200 | 300 | |
| V.22bis | Dialup | 2400 | 1200 | Compatible with V.22. |
| V.23 | Dialup | 1200 | 600 | Specifies 75-bps reverse channel. |
| V.27ter | Dialup | 2400 4.8Kbps | 2400 ... |
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.