diff --git a/app/src/main/java/com/nextcloud/talk/adapters/items/ContactItem.java b/app/src/main/java/com/nextcloud/talk/adapters/items/ContactItem.java
index a6f27fd92..998243f99 100644
--- a/app/src/main/java/com/nextcloud/talk/adapters/items/ContactItem.java
+++ b/app/src/main/java/com/nextcloud/talk/adapters/items/ContactItem.java
@@ -35,10 +35,6 @@ import eu.davidea.viewholders.FlexibleViewHolder;
 public class ContactItem extends AbstractFlexibleItem<ContactItem.ContactItemViewHolder> implements
     ISectionable<ContactItem.ContactItemViewHolder, GenericTextHeaderItem>, IFilterable<String> {
 
-    public static final String PARTICIPANT_SOURCE_CIRCLES = "circles";
-    public static final String PARTICIPANT_SOURCE_GROUPS = "groups";
-    public static final String PARTICIPANT_SOURCE_USERS = "users";
-
     private final Participant participant;
     private final User user;
     private GenericTextHeaderItem header;
@@ -133,9 +129,7 @@ public class ContactItem extends AbstractFlexibleItem<ContactItem.ContactItemVie
 
         if (
             participant.getCalculatedActorType() == Participant.ActorType.GROUPS ||
-                PARTICIPANT_SOURCE_GROUPS.equals(participant.getSource()) ||
-                participant.getCalculatedActorType() == Participant.ActorType.CIRCLES ||
-                PARTICIPANT_SOURCE_CIRCLES.equals(participant.getSource())) {
+                participant.getCalculatedActorType() == Participant.ActorType.CIRCLES) {
 
             setGenericAvatar(holder, R.drawable.ic_avatar_group, R.drawable.ic_circular_group);
 
@@ -163,10 +157,12 @@ public class ContactItem extends AbstractFlexibleItem<ContactItem.ContactItemVie
             }
 
             ImageViewExtensionsKt.loadUserAvatar(holder.binding.avatarView, user, displayName, true, false);
-        } else if (participant.getCalculatedActorType() == Participant.ActorType.USERS ||
-            PARTICIPANT_SOURCE_USERS.equals(participant.getSource())) {
-            ImageViewExtensionsKt.loadUserAvatar(holder.binding.avatarView, user, participant.getCalculatedActorId(),
-                                                 true, false);
+        } else if (participant.getCalculatedActorType() == Participant.ActorType.USERS) {
+            ImageViewExtensionsKt.loadUserAvatar(holder.binding.avatarView,
+                                                 user,
+                                                 participant.getCalculatedActorId(),
+                                                 true,
+                                                 false);
         }
     }
 
diff --git a/app/src/main/java/com/nextcloud/talk/adapters/items/ParticipantItem.kt b/app/src/main/java/com/nextcloud/talk/adapters/items/ParticipantItem.kt
index 71cbfccdf..9b3b20ac2 100644
--- a/app/src/main/java/com/nextcloud/talk/adapters/items/ParticipantItem.kt
+++ b/app/src/main/java/com/nextcloud/talk/adapters/items/ParticipantItem.kt
@@ -114,8 +114,13 @@ class ParticipantItem(
         ) {
             holder.binding.nameText.text = sharedApplication!!.getString(R.string.nc_guest)
         }
-        if (model.calculatedActorType == Participant.ActorType.GROUPS || "groups" == model.source ||
-            model.calculatedActorType == Participant.ActorType.CIRCLES || "circles" == model.source
+
+        // when(){        // check if    model.source    can be removed!
+        //
+        // }
+
+        if (model.calculatedActorType == Participant.ActorType.GROUPS ||
+            model.calculatedActorType == Participant.ActorType.CIRCLES
         ) {
             holder.binding.avatarView.loadDefaultGroupCallAvatar(viewThemeUtils)
         } else if (model.calculatedActorType == Participant.ActorType.EMAILS) {
@@ -129,10 +134,11 @@ class ParticipantItem(
                 displayName = model.displayName
             }
             holder.binding.avatarView.loadGuestAvatar(user, displayName!!, false)
-        } else if (model.calculatedActorType == Participant.ActorType.USERS || "users" == model.source) {
+        } else if (model.calculatedActorType == Participant.ActorType.USERS) {
             holder.binding.avatarView
                 .loadUserAvatar(user, model.calculatedActorId!!, true, false)
         }
+
         val resources = sharedApplication!!.resources
         val inCallFlag = model.inCall
         if (inCallFlag and InCallFlags.WITH_PHONE.toLong() > 0) {
diff --git a/app/src/main/java/com/nextcloud/talk/contacts/ContactsActivity.kt b/app/src/main/java/com/nextcloud/talk/contacts/ContactsActivity.kt
index 8ac2f21f4..5d6f44c4b 100644
--- a/app/src/main/java/com/nextcloud/talk/contacts/ContactsActivity.kt
+++ b/app/src/main/java/com/nextcloud/talk/contacts/ContactsActivity.kt
@@ -574,7 +574,6 @@ class ContactsActivity :
         participant.actorId = autocompleteUser.id
         participant.actorType = actorTypeConverter.getFromString(autocompleteUser.source)
         participant.displayName = autocompleteUser.label
-        participant.source = autocompleteUser.source
 
         return participant
     }
@@ -593,30 +592,30 @@ class ContactsActivity :
                 (o2 as GenericTextHeaderItem).model
             }
             if (o1 is ContactItem && o2 is ContactItem) {
-                val firstSource: String = o1.model.source!!
-                val secondSource: String = o2.model.source!!
+                val firstSource: Participant.ActorType = o1.model.actorType!!
+                val secondSource: Participant.ActorType = o2.model.actorType!!
                 if (firstSource == secondSource) {
                     return@sort firstName.compareTo(secondName, ignoreCase = true)
                 }
 
                 // First users
-                if ("users" == firstSource) {
+                if (Participant.ActorType.USERS == firstSource) {
                     return@sort -1
-                } else if ("users" == secondSource) {
+                } else if (Participant.ActorType.USERS == secondSource) {
                     return@sort 1
                 }
 
                 // Then groups
-                if ("groups" == firstSource) {
+                if (Participant.ActorType.GROUPS == firstSource) {
                     return@sort -1
-                } else if ("groups" == secondSource) {
+                } else if (Participant.ActorType.GROUPS == secondSource) {
                     return@sort 1
                 }
 
                 // Then circles
-                if ("circles" == firstSource) {
+                if (Participant.ActorType.CIRCLES == firstSource) {
                     return@sort -1
-                } else if ("circles" == secondSource) {
+                } else if (Participant.ActorType.CIRCLES == secondSource) {
                     return@sort 1
                 }
 
@@ -638,13 +637,13 @@ class ContactsActivity :
                 (o2 as GenericTextHeaderItem).model
             }
             if (o1 is ContactItem && o2 is ContactItem) {
-                if ("groups" == o1.model.source &&
-                    "groups" == o2.model.source
+                if (Participant.ActorType.GROUPS == o1.model.actorType &&
+                    Participant.ActorType.GROUPS == o2.model.actorType
                 ) {
                     return@sort firstName.compareTo(secondName, ignoreCase = true)
-                } else if ("groups" == o1.model.source) {
+                } else if (Participant.ActorType.GROUPS == o1.model.actorType) {
                     return@sort -1
-                } else if ("groups" == o2.model.source) {
+                } else if (Participant.ActorType.GROUPS == o2.model.actorType) {
                     return@sort 1
                 }
             }
@@ -775,7 +774,7 @@ class ContactsActivity :
 
     private fun createRoom(contactItem: ContactItem) {
         var roomType = "1"
-        if ("groups" == contactItem.model.source) {
+        if (Participant.ActorType.GROUPS == contactItem.model.actorType) {
             roomType = "2"
         }
         val apiVersion: Int = ApiUtils.getConversationApiVersion(currentUser!!, intArrayOf(ApiUtils.API_V4, 1))
@@ -817,19 +816,19 @@ class ContactsActivity :
     }
 
     private fun updateSelectionLists(participant: Participant) {
-        if ("groups" == participant.source) {
+        if (Participant.ActorType.GROUPS == participant.actorType) {
             if (participant.selected) {
                 selectedGroupIds.add(participant.calculatedActorId!!)
             } else {
                 selectedGroupIds.remove(participant.calculatedActorId!!)
             }
-        } else if ("emails" == participant.source) {
+        } else if (Participant.ActorType.EMAILS == participant.actorType) {
             if (participant.selected) {
                 selectedEmails.add(participant.calculatedActorId!!)
             } else {
                 selectedEmails.remove(participant.calculatedActorId!!)
             }
-        } else if ("circles" == participant.source) {
+        } else if (Participant.ActorType.CIRCLES == participant.actorType) {
             if (participant.selected) {
                 selectedCircleIds.add(participant.calculatedActorId!!)
             } else {
@@ -849,7 +848,8 @@ class ContactsActivity :
         participant: Participant,
         adapter: FlexibleAdapter<*>?
     ): Boolean {
-        return "groups" == contactItem.model.source && participant.selected && adapter?.selectedItemCount!! > 1
+        return Participant.ActorType.GROUPS == contactItem.model.actorType &&
+            participant.selected && adapter?.selectedItemCount!! > 1
     }
 
     private fun listOpenConversations() {
@@ -869,7 +869,7 @@ class ContactsActivity :
         for (i in 0 until adapter!!.itemCount) {
             if (adapter?.getItem(i) is ContactItem) {
                 val contactItem: ContactItem = adapter?.getItem(i) as ContactItem
-                if ("groups" == contactItem.model.source) {
+                if (Participant.ActorType.GROUPS == contactItem.model.actorType) {
                     contactItem.isEnabled = !isPublicCall
                 }
             }
diff --git a/app/src/main/java/com/nextcloud/talk/models/json/participants/Participant.kt b/app/src/main/java/com/nextcloud/talk/models/json/participants/Participant.kt
index acbb16f85..11b92d61e 100644
--- a/app/src/main/java/com/nextcloud/talk/models/json/participants/Participant.kt
+++ b/app/src/main/java/com/nextcloud/talk/models/json/participants/Participant.kt
@@ -72,8 +72,6 @@ data class Participant(
     @JsonField(name = ["statusMessage"])
     var statusMessage: String? = null,
 
-    var source: String? = null,
-
     var selected: Boolean = false
 ) : Parcelable {
     // This constructor is added to work with the 'com.bluelinelabs.logansquare.annotation.JsonObject'
@@ -84,7 +82,7 @@ data class Participant(
     )
 
     /**
-     * actorType is only guaranteed in APIv3+ so use calculatedActorId
+     * actorType is only guaranteed in APIv3+ so use calculatedActorType
      *
      * https://github.com/nextcloud/spreed/blob/stable21/lib/Controller/RoomController.php#L1145-L1148
      */