1. What is a party line?
2. What is usually understood by private lines?
3. What problem is there to overcome in connection with party lines?
4. State the two general classes of party-line systems.
5. Point out the defects of the series system.
6. Make sketch of a metallic bridging line and show the circuit for the voice currents.
7. What is a signal code?
8. Give classification of selective party-line systems with short definitions.
9. Describe the principle of selection by polarity and make sketch illustrating this principle.