diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0a74c0d19..73ea5973a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 * Better incoming call system integration
 * Calls are not experimental anymore and don't need to be manually enabled
 * Calls can be answered by tapping messages
+* Notify the user when they try to make a call while the device is offline
 * Channels are no longer experimental and are available by default
 * Display a permanent notification when doing location streaming and get rid of dangerous "Access Location in Background" permission
 * Autoplay all voice messages in a chat
diff --git a/src/main/java/org/thoughtcrime/securesms/ConversationActivity.java b/src/main/java/org/thoughtcrime/securesms/ConversationActivity.java
index 384add495..5746bcb06 100644
--- a/src/main/java/org/thoughtcrime/securesms/ConversationActivity.java
+++ b/src/main/java/org/thoughtcrime/securesms/ConversationActivity.java
@@ -633,12 +633,12 @@ public class ConversationActivity extends PassphraseRequiredActionBarActivity
       return true;
     } else if (itemId == R.id.menu_start_audio_call) {
       if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
-        CallUtil.startAudioCall(context, chatId);
+        CallUtil.startAudioCall(this, chatId);
       }
       return true;
     } else if (itemId == R.id.menu_start_video_call) {
       if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
-        CallUtil.startVideoCall(context, chatId);
+        CallUtil.startVideoCall(this, chatId);
       }
       return true;
     } else if (itemId == R.id.menu_all_media) {
diff --git a/src/main/java/org/thoughtcrime/securesms/calls/CallUtil.java b/src/main/java/org/thoughtcrime/securesms/calls/CallUtil.java
index 91d3018e5..fe5a57c72 100644
--- a/src/main/java/org/thoughtcrime/securesms/calls/CallUtil.java
+++ b/src/main/java/org/thoughtcrime/securesms/calls/CallUtil.java
@@ -5,13 +5,18 @@ import android.content.Intent;
 import android.graphics.Bitmap;
 import android.graphics.drawable.Drawable;
 import android.graphics.drawable.Icon;
+import android.net.ConnectivityManager;
+import android.net.Network;
+import android.net.NetworkCapabilities;
 import android.os.Build;
 import android.util.Log;
 import android.widget.Toast;
 import androidx.annotation.Nullable;
 import androidx.annotation.RequiresApi;
+import androidx.appcompat.app.AlertDialog;
 import androidx.core.telecom.CallEndpointCompat;
 import com.b44t.messenger.DcChat;
+import com.b44t.messenger.DcContext;
 import com.bumptech.glide.load.engine.DiskCacheStrategy;
 import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.connect.DcHelper;
@@ -52,8 +57,22 @@ public class CallUtil {
       return;
     }
 
-    int accId = DcHelper.getContext(context).getAccountId();
-    coordinator.initiateOutgoingCall(accId, chatId, startsWithVideo);
+    Runnable proceedWithCall =
+        () -> {
+          int accId = DcHelper.getContext(context).getAccountId();
+          coordinator.initiateOutgoingCall(accId, chatId, startsWithVideo);
+        };
+
+    if (!isNetworkAvailable(context)) {
+      new AlertDialog.Builder(context)
+          .setMessage(context.getString(R.string.call_requires_connection))
+          .setPositiveButton(R.string.perm_continue, (dialog, which) -> proceedWithCall.run())
+          .setNegativeButton(android.R.string.cancel, null)
+          .show();
+      return;
+    }
+
+    proceedWithCall.run();
   }
 
   @Nullable
@@ -138,4 +157,24 @@ public class CallUtil {
     }
     return iconRes;
   }
+
+  @RequiresApi(api = Build.VERSION_CODES.M)
+  private static boolean isNetworkAvailable(Context context) {
+    ConnectivityManager manager =
+        (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
+    if (manager == null) return true;
+
+    boolean networkAvailable = false;
+    Network network = manager.getActiveNetwork();
+    if (network != null) {
+      NetworkCapabilities caps = manager.getNetworkCapabilities(network);
+      networkAvailable =
+          caps != null && caps.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET);
+    }
+
+    boolean serverConnected =
+        DcHelper.getContext(context).getConnectivity() >= DcContext.DC_CONNECTIVITY_WORKING;
+
+    return networkAvailable || serverConnected;
+  }
 }
diff --git a/src/main/res/values/strings.xml b/src/main/res/values/strings.xml
index e349fb327..e0fc8978d 100644
--- a/src/main/res/values/strings.xml
+++ b/src/main/res/values/strings.xml
@@ -438,6 +438,7 @@
     <string name="call_answered_elsewhere">Call answered on another device</string>
     <string name="call_requires_camera_permission">Camera permission is required for video calls</string>
     <string name="call_requires_mic_permission">Microphone permission is required for calls</string>
+    <string name="call_requires_connection">Cannot start call. Make sure your device has an internet connection and try again.</string>
     <!-- Used e.g. in a notifications to describe an ongoing call. "Call" is a noun here, in the meaning of "This is the call with ..." where the placeholder is replaced by the name of the contact. -->
     <string name="call_with">Call with %1$s</string>
     <!-- Use e.g. in a notifications during ringing. Placeholder is relaced by the name of the contact being called. -->