Q.List the sequence of operations involved in establishing a call from a cell phone.

Making a cell-phone call involves an automatic exchange of signals between the handset, its cell and the MTSO before and during the conversation, following a fixed sequence of steps.

[!ANSWER]

The sequence is: (1) the user powers the unit ON, turning on the transmitter and receiver; (2) the receiver seeks an open control channel through the MTSO, which verifies the caller as a valid number; (3) the user enters the number on the keypad; (4) the user sends the number by pressing the call button; (5) the cell and MTSO find an open channel and send the frequency data to a transceiver; (6) transmitter power is adjusted and handshake signals are exchanged to confirm contact; (7) the MTSO calls the designated number and conversation takes place; (8) if the mobile moves between cells, the MTSO performs call hand-off to maintain signal strength; (9) at the end, the call is terminated by pressing the power button again.

[!TLDR]

A call is set up in nine steps from powering on and finding a control channel, through dialling and handshaking, to conversation with hand-off, and finally termination.

When a person initiates a cell-phone call, the following sequence of operations takes place:

1. The user powers the unit, which turns ON both the transmitter and the receiver.
2. The receiver seeks an open control channel through the MTSO, which verifies that the caller is a valid number entitled to service.
3. The user enters the desired number using the keypad/keyboard.
4. The user sends the number by pressing the call button.
5. The cell and the MTSO search for an open voice channel and send the frequency data to a cellular transceiver.
6. The transmitter power is adjusted and handshake signals are exchanged, signifying that contact has been established.
7. The MTSO calls the designated number and the conversation takes place.
8. If the mobile passes from one cell to another during the call, the MTSO performs call hand-off to maintain maximum signal strength.
9. At the end of the conversation, the call is terminated by pressing the power button again.

[!ANSWER]

The nine steps are: (1) power the unit ON (transmitter and receiver ON); (2) the receiver seeks an open control channel through the MTSO, which verifies the caller; (3) the user enters the number; (4) the user presses the call button to send it; (5) the cell and MTSO find an open channel and send frequency data to a transceiver; (6) transmitter power is adjusted and handshake signals confirm contact; (7) the MTSO calls the number and conversation takes place; (8) the MTSO performs call hand-off if the mobile moves between cells; and (9) the call is terminated by pressing the power button again.