1 files changed, 6 insertions, 2 deletions
diff --git a/src/org/traccar/protocol/T55ProtocolDecoder.java b/src/org/traccar/protocol/T55ProtocolDecoder.java
index dee7210b1..6b4ee6ebd 100644
--- a/src/org/traccar/protocol/T55ProtocolDecoder.java
+++ b/src/org/traccar/protocol/T55ProtocolDecoder.java
@@ -18,6 +18,7 @@ package org.traccar.protocol;
 import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.socket.DatagramChannel;
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.Context;
 import org.traccar.DeviceSession;
 import org.traccar.helper.DateBuilder;
 import org.traccar.helper.Parser;
@@ -98,8 +99,11 @@ public class T55ProtocolDecoder extends BaseProtocolDecoder {
     private Position decodeGprmc(
             DeviceSession deviceSession, String sentence, SocketAddress remoteAddress, Channel channel) {
 
-        if (channel != null && !(channel instanceof DatagramChannel)) {
-            channel.write("OK1\r\n");
+        if (deviceSession != null && channel != null && !(channel instanceof DatagramChannel)) {
+            if (Context.getIdentityManager().lookupAttributeBoolean(
+                    deviceSession.getDeviceId(), getProtocolName() + ".ack", false, true)) {
+                channel.write("OK1\r\n");
+            }
         }
 
         Parser parser = new Parser(PATTERN_GPRMC, sentence);