diff --git a/app/src/main/kotlin/com/simplemobiletools/dialer/activities/CallActivity.kt b/app/src/main/kotlin/com/simplemobiletools/dialer/activities/CallActivity.kt
index 80d034bd..3148920f 100644
--- a/app/src/main/kotlin/com/simplemobiletools/dialer/activities/CallActivity.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/dialer/activities/CallActivity.kt
@@ -23,9 +23,7 @@ import com.simplemobiletools.commons.helpers.isOreoMr1Plus
 import com.simplemobiletools.commons.helpers.isOreoPlus
 import com.simplemobiletools.dialer.R
 import com.simplemobiletools.dialer.extensions.*
-import com.simplemobiletools.dialer.helpers.CallContactAvatarHelper
-import com.simplemobiletools.dialer.helpers.CallManager
-import com.simplemobiletools.dialer.helpers.CallManagerListener
+import com.simplemobiletools.dialer.helpers.*
 import com.simplemobiletools.dialer.models.CallContact
 import kotlinx.android.synthetic.main.activity_call.*
 import kotlinx.android.synthetic.main.dialpad.*
@@ -57,6 +55,11 @@ class CallActivity : SimpleActivity() {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_call)
 
+        if (CallManager.call == null) {
+            finish()
+            return
+        }
+
         updateTextColors(call_holder)
         initButtons()
 
@@ -65,13 +68,13 @@ class CallActivity : SimpleActivity() {
         addLockScreenFlags()
 
         CallManager.addListener(callCallback)
+
+        updateCallContactInfo(CallManager.getPrimaryCall())
     }
 
     override fun onResume() {
         super.onResume()
-        updateCallState(CallManager.getPrimaryCall())
-        updateCallOnHoldState(CallManager.getSecondaryCall())
-        updateCallContactInfo(CallManager.getPrimaryCall())
+        updateState()
     }
 
     override fun onDestroy() {
@@ -171,7 +174,10 @@ class CallActivity : SimpleActivity() {
         dialpad_hashtag_holder.setOnClickListener { dialpadPressed('#') }
 
         dialpad_wrapper.setBackgroundColor(getProperBackgroundColor())
-        arrayOf(call_toggle_microphone, call_toggle_speaker, call_dialpad, dialpad_close, call_sim_image).forEach {
+        arrayOf(
+            call_toggle_microphone, call_toggle_speaker, call_dialpad, dialpad_close,
+            call_sim_image, call_toggle_hold, call_add, call_swap, call_merge, call_manage
+        ).forEach {
             it.applyColorFilter(getProperTextColor())
         }
 
@@ -410,11 +416,23 @@ class CallActivity : SimpleActivity() {
         if (statusTextId != 0) {
             call_status_label.text = getString(statusTextId)
         }
+    }
 
-        val isSingleCallActionsEnabled = (state == Call.STATE_ACTIVE || state == Call.STATE_DISCONNECTED
-            || state == Call.STATE_DISCONNECTING || state == Call.STATE_HOLDING)
-        setActionButtonEnabled(call_toggle_hold, isSingleCallActionsEnabled)
-        setActionButtonEnabled(call_add, isSingleCallActionsEnabled)
+    private fun updateState() {
+        val phoneState = CallManager.getPhoneState()
+        if (phoneState is SingleCall) {
+            updateCallState(phoneState.call)
+            updateCallOnHoldState(null)
+            val state = phoneState.call.getStateCompat()
+            val isSingleCallActionsEnabled = (state == Call.STATE_ACTIVE || state == Call.STATE_DISCONNECTED
+                || state == Call.STATE_DISCONNECTING || state == Call.STATE_HOLDING)
+            setActionButtonEnabled(call_toggle_hold, isSingleCallActionsEnabled)
+            setActionButtonEnabled(call_add, isSingleCallActionsEnabled)
+            call_manage.beVisibleIf(phoneState.call.isConference())
+        } else if (phoneState is TwoCalls) {
+            updateCallState(phoneState.active)
+            updateCallOnHoldState(phoneState.onHold)
+        }
     }
 
     private fun updateCallOnHoldState(call: Call?) {
@@ -427,17 +445,23 @@ class CallActivity : SimpleActivity() {
             }
         }
         on_hold_status_holder.beVisibleIf(hasCallOnHold)
-        controls_single_call.beVisibleIf(!hasCallOnHold) // TODO and not conference
+        controls_single_call.beVisibleIf(!hasCallOnHold)
         controls_two_calls.beVisibleIf(hasCallOnHold)
     }
 
     private fun updateCallContactInfo(call: Call?) {
-        CallManager.getCallContact(applicationContext, call) { contact ->
-            callContact = contact
-            val avatar = callContactAvatarHelper.getCallContactAvatar(contact)
-            runOnUiThread {
-                updateOtherPersonsInfo(avatar)
-                checkCalledSIMCard()
+        if (call.isConference()) {
+            caller_avatar.setImageDrawable(null)
+            caller_number.text = null
+            caller_name_label.text = getString(R.string.conference)
+        } else {
+            CallManager.getCallContact(applicationContext, call) { contact ->
+                callContact = contact
+                val avatar = callContactAvatarHelper.getCallContactAvatar(contact)
+                runOnUiThread {
+                    updateOtherPersonsInfo(avatar)
+                    checkCalledSIMCard()
+                }
             }
         }
     }
@@ -502,17 +526,12 @@ class CallActivity : SimpleActivity() {
 
     private val callCallback = object : CallManagerListener {
         override fun onStateChanged(call: Call, state: Int) {
-            updateCallState(call)
+            updateState()
         }
 
-        override fun onCallPutOnHold(call: Call?) {
-            updateCallOnHoldState(call)
-        }
-
-        override fun onCallsChanged(active: Call, onHold: Call?) {
-            updateCallState(active)
-            updateCallOnHoldState(onHold)
-            updateCallContactInfo(active)
+        override fun onPrimaryCallChanged(call: Call) {
+            updateCallContactInfo(call)
+            updateState()
         }
     }
 
diff --git a/app/src/main/kotlin/com/simplemobiletools/dialer/helpers/CallManager.kt b/app/src/main/kotlin/com/simplemobiletools/dialer/helpers/CallManager.kt
index 4349d195..e8f7c996 100644
--- a/app/src/main/kotlin/com/simplemobiletools/dialer/helpers/CallManager.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/dialer/helpers/CallManager.kt
@@ -12,6 +12,8 @@ import com.simplemobiletools.commons.helpers.MyContactsContentProvider
 import com.simplemobiletools.commons.helpers.SimpleContactsHelper
 import com.simplemobiletools.commons.helpers.ensureBackgroundThread
 import com.simplemobiletools.dialer.extensions.getStateCompat
+import com.simplemobiletools.dialer.extensions.hasCapability
+import com.simplemobiletools.dialer.extensions.isConference
 import com.simplemobiletools.dialer.models.CallContact
 import java.util.concurrent.CopyOnWriteArraySet
 
@@ -28,37 +30,73 @@ class CallManager {
         fun onCallAdded(call: Call) {
             this.call = call
             calls.add(call)
+            for (listener in listeners) {
+                listener.onPrimaryCallChanged(call)
+            }
             call.registerCallback(object : Call.Callback() {
                 override fun onStateChanged(call: Call, state: Int) {
                     Log.d(TAG, "onStateChanged: $call")
+                    updateState()
                     for (listener in listeners) {
                         listener.onStateChanged(call, state)
                     }
-                    if (state == Call.STATE_HOLDING && calls.size > 1) {
-                        for (listener in listeners) {
-                            listener.onCallPutOnHold(call)
-                        }
-                    }
-                    if (state == Call.STATE_ACTIVE && calls.size == 1) {
-                        for (listener in listeners) {
-                            listener.onCallPutOnHold(null)
-                        }
-                    }
-                    if ((state == Call.STATE_CONNECTING || state == Call.STATE_DIALING || state == Call.STATE_ACTIVE) && calls.size > 1) {
-                        if (CallManager.call != call) {
-                            CallManager.call = call
-                            Log.d(TAG, "onCallsChanged")
-                            for (listener in listeners) {
-                                listener.onCallsChanged(call, getSecondaryCall())
-                            }
-                        }
-                    }
+                }
+
+                override fun onConferenceableCallsChanged(call: Call, conferenceableCalls: MutableList<Call>) {
+                    Log.d(TAG, "onConferenceableCallsChanged: $call, conferenceableCalls size=${conferenceableCalls.size}")
+                    updateState()
                 }
             })
         }
 
         fun onCallRemoved(call: Call) {
             calls.remove(call)
+            updateState()
+        }
+
+        fun getPhoneState(): PhoneState {
+            return when (calls.size) {
+                0 -> {
+                    NoCall
+                }
+                1 -> {
+                    SingleCall(calls.first())
+                }
+                2 -> {
+                    val active = calls.find { it.getStateCompat() == Call.STATE_ACTIVE }
+                    val newCall = calls.find { it.getStateCompat() == Call.STATE_CONNECTING || it.getStateCompat() == Call.STATE_DIALING }
+                    val onHold = calls.find { it.getStateCompat() == Call.STATE_HOLDING }
+                    if (active != null && newCall != null) {
+                        TwoCalls(newCall, active)
+                    } else if(newCall != null && onHold != null) {
+                        TwoCalls(newCall, onHold)
+                    } else if(active != null && onHold != null) {
+                        TwoCalls(active, onHold)
+                    } else {
+                        TwoCalls(calls[0], calls[1])
+                    }
+                }
+                else -> {
+                    SingleCall(calls.find { it.isConference() }!!)
+                    // TODO handle the call on hold (outside the conference)
+                }
+            }
+        }
+
+        private fun updateState() {
+            val primaryCall = when (val phoneState = getPhoneState()) {
+                is NoCall -> null
+                is SingleCall -> phoneState.call
+                is TwoCalls -> phoneState.active
+            }
+            if (primaryCall == null) {
+                call = null
+            } else if (primaryCall != call) {
+                call = primaryCall
+                for (listener in listeners) {
+                    listener.onPrimaryCallChanged(primaryCall)
+                }
+            }
         }
 
         fun getPrimaryCall(): Call? {
@@ -104,14 +142,14 @@ class CallManager {
         }
 
         fun merge() {
-//            val conferenceableCalls = call!!.conferenceableCalls
-//            if (conferenceableCalls.isNotEmpty()) {
-//                call!!.conference(conferenceableCalls.first())
-//            } else {
-//                if (call!!.hasCapability(Call.Details.CAPABILITY_MERGE_CONFERENCE)) {
-//                    call!!.mergeConference()
-//                }
-//            }
+            val conferenceableCalls = call!!.conferenceableCalls
+            if (conferenceableCalls.isNotEmpty()) {
+                call!!.conference(conferenceableCalls.first())
+            } else {
+                if (call!!.hasCapability(Call.Details.CAPABILITY_MERGE_CONFERENCE)) {
+                    call!!.mergeConference()
+                }
+            }
         }
 
         fun addListener(listener: CallManagerListener) {
@@ -203,6 +241,10 @@ class CallManager {
 
 interface CallManagerListener {
     fun onStateChanged(call: Call, state: Int)
-    fun onCallPutOnHold(call: Call?)
-    fun onCallsChanged(active: Call, onHold: Call?)
+    fun onPrimaryCallChanged(call: Call)
 }
+
+sealed class PhoneState
+object NoCall : PhoneState()
+class SingleCall(val call: Call?) : PhoneState()
+class TwoCalls(val active: Call, val onHold: Call) : PhoneState()
diff --git a/app/src/main/kotlin/com/simplemobiletools/dialer/services/CallService.kt b/app/src/main/kotlin/com/simplemobiletools/dialer/services/CallService.kt
index d3912049..0bcddd5d 100644
--- a/app/src/main/kotlin/com/simplemobiletools/dialer/services/CallService.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/dialer/services/CallService.kt
@@ -46,8 +46,6 @@ class CallService : InCallService() {
             CallManager.inCallService = null
             callNotificationManager.cancelNotification()
         } else {
-            // TODO if left more than 1
-            CallManager.call = CallManager.calls.first()
             callNotificationManager.setupNotification()
             startActivity(CallActivity.getStartIntent(this))
         }
diff --git a/app/src/main/res/drawable/ic_people_vector.xml b/app/src/main/res/drawable/ic_people_vector.xml
deleted file mode 100644
index 4910d920..00000000
--- a/app/src/main/res/drawable/ic_people_vector.xml
+++ /dev/null
@@ -1,12 +0,0 @@
-<vector android:height="24dp" android:tint="#FFFFFF"
-    android:viewportHeight="24" android:viewportWidth="24"
-    android:width="24dp" xmlns:android="http://schemas.android.com/apk/res/android">
-    <path android:fillColor="@android:color/white"
-        android:fillType="evenOdd" android:pathData="M16.67,13.13C18.04,14.06 19,15.32 19,17v3h4v-3C23,14.82 19.43,13.53 16.67,13.13z"/>
-    <path android:fillColor="@android:color/white"
-        android:fillType="evenOdd" android:pathData="M9,8m-4,0a4,4 0,1 1,8 0a4,4 0,1 1,-8 0"/>
-    <path android:fillColor="@android:color/white"
-        android:fillType="evenOdd" android:pathData="M15,12c2.21,0 4,-1.79 4,-4c0,-2.21 -1.79,-4 -4,-4c-0.47,0 -0.91,0.1 -1.33,0.24C14.5,5.27 15,6.58 15,8s-0.5,2.73 -1.33,3.76C14.09,11.9 14.53,12 15,12z"/>
-    <path android:fillColor="@android:color/white"
-        android:fillType="evenOdd" android:pathData="M9,13c-2.67,0 -8,1.34 -8,4v3h16v-3C17,14.34 11.67,13 9,13z"/>
-</vector>
diff --git a/app/src/main/res/layout/activity_call.xml b/app/src/main/res/layout/activity_call.xml
index 7d73de8f..bf927509 100644
--- a/app/src/main/res/layout/activity_call.xml
+++ b/app/src/main/res/layout/activity_call.xml
@@ -118,6 +118,7 @@
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:layout_margin="@dimen/normal_margin"
+            android:contentDescription="@null"
             app:layout_constraintBottom_toBottomOf="parent"
             app:layout_constraintStart_toStartOf="parent"
             app:layout_constraintTop_toTopOf="parent"
@@ -203,6 +204,7 @@
             android:layout_height="@dimen/dialpad_button_size"
             android:layout_marginTop="@dimen/bigger_margin"
             android:background="?attr/selectableItemBackgroundBorderless"
+            android:contentDescription="@string/hold_call"
             android:padding="@dimen/medium_margin"
             android:src="@drawable/ic_pause_vector"
             app:layout_constraintEnd_toStartOf="@id/call_add"
@@ -215,6 +217,7 @@
             android:layout_height="@dimen/dialpad_button_size"
             android:layout_marginTop="@dimen/bigger_margin"
             android:background="?attr/selectableItemBackgroundBorderless"
+            android:contentDescription="@string/call_add"
             android:padding="@dimen/medium_margin"
             android:src="@drawable/ic_add_call_vector"
             app:layout_constraintEnd_toEndOf="@id/call_manage"
@@ -227,6 +230,7 @@
             android:layout_height="@dimen/dialpad_button_size"
             android:layout_marginTop="@dimen/bigger_margin"
             android:background="?attr/selectableItemBackgroundBorderless"
+            android:contentDescription="@string/call_manage"
             android:padding="@dimen/medium_margin"
             android:src="@drawable/ic_people_vector"
             android:visibility="gone"
@@ -240,6 +244,7 @@
             android:layout_height="@dimen/dialpad_button_size"
             android:layout_marginTop="@dimen/bigger_margin"
             android:background="?attr/selectableItemBackgroundBorderless"
+            android:contentDescription="@string/call_swap"
             android:padding="@dimen/medium_margin"
             android:src="@drawable/ic_call_swap_vector"
             app:layout_constraintEnd_toStartOf="@+id/call_merge"
@@ -254,6 +259,7 @@
             android:layout_height="@dimen/dialpad_button_size"
             android:layout_marginTop="@dimen/bigger_margin"
             android:background="?attr/selectableItemBackgroundBorderless"
+            android:contentDescription="@string/call_merge"
             android:padding="@dimen/medium_margin"
             android:src="@drawable/ic_call_merge_vector"
             app:layout_constraintEnd_toEndOf="parent"
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 928b9370..49689d9a 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -51,6 +51,12 @@
     <string name="hold_call">Hold call</string>
     <string name="resume_call">Resume call</string>
     <string name="call_on_hold">On Hold</string>
+    <string name="call_swap">Swap calls</string>
+    <string name="call_merge">Merge calls</string>
+    <string name="call_split">Split call</string>
+    <string name="call_add">Add call</string>
+    <string name="call_manage">Manage calls</string>
+    <string name="conference">Conference</string>
 
     <!-- Speed dial -->
     <string name="speed_dial">Speed dial</string>