What do you meant by signalling? Briefly explain the function of a signalling. Describe the subscriber line signalling used for analogue telephony. Describe the advantages of common channel signalling. Explain the following terms: i. Inter register signalling. ii. Link by link signalling. iii. End to end signalling. Draw a diagram for the SS7 protocol architecture. List the four classes of the signalling connection control part (SCCP) service, which are available and explain each one briefly. Define meta-signalling and explain it is use. Describe the function of the SAAL and its SSCOP sublayer. Explain how channel associated signalling was performed using PCM multi-frames.