Discuss the various enhanced services that can be made available to the subscribers because of stored program control.

One of the instant benefits of stored program control is as a host of new services can be made obtainable to the subscriber. They can be grouped in four types:

1. Services related with the calling subscriber and designed to decrease the time spent on dialling and dialling number's errors.

a. Abbreviated dialling

b. Recorded number calls or no dialing calls

c. Call back while free

 2. Services connected with the called subscriber and designed to raise the call completion rate.

a. Call forwarding

b. Operator answer

3. Services including more than two parties.

a. Calling the number record

b. Call waiting

c. Consultation hold

d. Conference calls

4. Miscellaneous

a. Automatic alarm

b. STD Barring

c. Malicious call tracing