Kotlin

Place a call

Add click listener code at of the onCreate inside MainActivity class:

startCallButton.setOnClickListener { startCall() }

To start the call after pressing start call button add the startCall method inside Mainctivity class:

@SuppressLint("MissingPermission")
fun startCall() {
  client.call(otherUser, NexmoCallHandler.SERVER, object : NexmoRequestListener<NexmoCall> {
      override fun onSuccess(call: NexmoCall?) {
          runOnUiThread { 
            hideUI()
            endCallButton.visibility = View.VISIBLE
          }

          onGoingCall = call

          onGoingCall?.addCallEventListener(object : NexmoCallEventListener {
              override fun onMemberStatusUpdated(callStatus: NexmoCallMemberStatus, nexmoMember: NexmoMember) {
                  if (callStatus == NexmoCallMemberStatus.COMPLETED || callStatus == NexmoCallMemberStatus.CANCELLED) {
                      onGoingCall = null

                      runOnUiThread { 
                          hideUI()
                          startCallButton.visibility = View.VISIBLE
                          waitingForIncomingCallTextView.visibility = View.VISIBLE
                      }
                  }
              }

              override fun onMuteChanged(nexmoMediaActionState: NexmoMediaActionState, nexmoMember: NexmoMember) {}

              override fun onEarmuffChanged(nexmoMediaActionState: NexmoMediaActionState, nexmoMember: NexmoMember) {}

              override fun onDTMF(dtmf: String, nexmoMember: NexmoMember) {}
          })
      }

      override fun onError(apiError: NexmoApiError) {
      }
  })
}

The above method starts the call. When the call is started (onSuccess callback) then addCallEventListener listener is added to a call instance. This way app can be notified about call status e.g. call end.

Webhooks

As you proceed with placing the call, please switch to the terminal and notice the /voice/answer endpoint being called to retrieve the NCCO:

NCCO request:
  - callee: 447700900000

Also, as the call progresses through various stages, /voice/event is being sent events:

...
---
VOICE EVENT:
{
  from: null,
  to: 'Alice',
  uuid: '2da93da3-bcac-47ee-b48e-4a18fae7db08',
  conversation_uuid: 'CON-1a28b1f8-0831-44e6-8d58-42739e7d4c77',
  status: 'started',
  direction: 'inbound',
  timestamp: '2021-03-10T10:36:21.285Z'
}
---
VOICE EVENT:
{
  headers: {},
  from: 'Alice',
  to: '447700900000',
  uuid: '8aa86e22-8d45-4201-b8d8-3dcd76e76429',
  conversation_uuid: 'CON-1a28b1f8-0831-44e6-8d58-42739e7d4c77',
  status: 'started',
  direction: 'outbound',
  timestamp: '2021-03-10T10:36:27.080Z'
}
---
...
---
VOICE EVENT:
{
  start_time: null,
  headers: {},
  rate: null,
  from: 'Alice',
  to: '447700900000',
  uuid: '8aa86e22-8d45-4201-b8d8-3dcd76e76429',
  conversation_uuid: 'CON-1a28b1f8-0831-44e6-8d58-42739e7d4c77',
  status: 'answered',
  direction: 'outbound',
  network: null,
  timestamp: '2021-03-10T10:36:31.604Z'
}
---
VOICE EVENT:
{
  headers: {},
  end_time: '2021-03-10T10:36:36.000Z',
  uuid: '8aa86e22-8d45-4201-b8d8-3dcd76e76429',
  network: '23433',
  duration: '5',
  start_time: '2021-03-10T10:36:31.000Z',
  rate: '0.10000000',
  price: '0.00833333',
  from: 'Unknown',
  to: '447700900000',
  conversation_uuid: 'CON-1a28b1f8-0831-44e6-8d58-42739e7d4c77',
  status: 'completed',
  direction: 'outbound',
  timestamp: '2021-03-10T10:36:35.585Z'
}
---
VOICE EVENT:
{
  headers: {},
  end_time: '2021-03-10T10:36:35.000Z',
  uuid: '2da93da3-bcac-47ee-b48e-4a18fae7db08',
  network: null,
  duration: '15',
  start_time: '2021-03-10T10:36:20.000Z',
  rate: '0.00',
  price: '0',
  from: null,
  to: 'Alice',
  conversation_uuid: 'CON-1a28b1f8-0831-44e6-8d58-42739e7d4c77',
  status: 'completed',
  direction: 'inbound',
  timestamp: '2021-03-10T10:36:36.187Z'
}

NOTE: As the call is completed, events will also contain duration and pricing information.

The end call button was shown to reflect the current state of the call:

End call
End call