The document discusses various aspects of telephone networks including analog switched service, analog leased service, analog hierarchy, switched/56 service, DDS, DS hierarchy, T-1 lines, T-1 frames, and fractional T-1 lines. Diagrams and figures are referenced throughout relating to these telephone network components and services.

1. Telephone Network Figure 8-17 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998

2. Figure 8-18 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998

3. Figure 8-19 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998

4. Analog Switched Service Figure 8-20 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998

5. Analog Leased Service Figure 8-21 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998

6. Analog Hierarchy Figure 8-22 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998

7. Figure 8-23 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998

8. Switched/56 Service Figure 8-24 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998

9. DDS Figure 8-25 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998

10. DS Hierarchy Figure 8-26 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998

11. T-1 Line Figure 8-27 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998

12. T-1 Frame Figure 8-28 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998

13. Fractional T-1 Line Figure 8-29 WCB/McGraw-Hill  The McGraw-Hill Companies, Inc., 1998