Scenarios

1. Initiate call
   1. Normal
   2. No channel available
   3. Busy destination
   4. Invalid destination number
2. Input number
   1. Normal
   2. Input wrong number
   3. Cancel
3. Make conversation
   1. Normal
4. Move
   1. Handoff
5. Terminate call
   1. User terminates call
   2. Callee terminates call
6. Acknowledge call
   1. Normal

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1. Initiate call
   1. Normal
      • User inputs destination number into a handset.
      • User pushes Talk button; the handset sends request to make a call to base station.
      • Base station accepts the call and starts to contact destination.
      • Destination phone rings.
      • Base station sends Ringback signal to the handset; the handset generates Ringback tone.
      • Destination user pickups the phone.
      • Base station sends Offhook signal to the handset; the handset starts sending and receiving voice.
   2. No channel available
      • User inputs destination number into a handset.
      • User pushes Talk button; the handset sends request to make a call to base station.
      • Base station rejects the call; the handset displays reject message.
   3. Busy destination
      • User inputs destination number into a handset.
      • User pushes Talk button; the handset sends request to make a call to base station.
      • Base station accepts the call and starts to contact destination.
      • Destination phone is busy.
      • Base station sends Busy signal to the handset; the handset generates Busy tone
   4. Invalid destination number
      • User inputs destination number into handset.
      • User pushes Talk button; handset sends request to make a call to base station.
      • Base station accepts the call and checks destination number.
      • Base station sends invalid number message to the handset; the handset displays the message.
2. Input number
   1. Normal
      • User pushes number buttons; handset display numbers on the display.
   2. Input wrong number
      • User pushes wrong number button.
      • User pushes Delete button; handset deletes last number on the display.
   3. Cancel
      • User inputs destination number into a handset.
      • User pushes End button; the handset clears all number and goes to ready state.
3. Make conversation
   1. Normal
      • User starts making conversation; handset sends and receives voice to and from base station.
4. Move
   1. Handoff
      • The signal strength received by handset drops beyond acceptable range.
      • Handset reports signal strengths to base station; base station initiates handoff.
      • Base station assigns a new base station and new voice and control channels; handset switches over to the new base station and channels.
5. Terminate call
   1. User terminates call
      • User pushes End button; handset sends Onhook signal to the base station.
      • Both base station and handset disconnect from voice channel.
      • The handset resets.
   2. Callee terminates call
      • Base station send Onhook signal to the handset; handset resets.
6. Acknowledge call
   1. Normal
      • Base station sends paging message; handset send acknowledgement back.
      • Handset starts ringing; user pushes Talk button to accept the call.