diff --git a/application/controllers/Contesting.php b/application/controllers/Contesting.php
index bcb9f46e..a32765ff 100644
--- a/application/controllers/Contesting.php
+++ b/application/controllers/Contesting.php
@@ -150,4 +150,24 @@ class Contesting extends CI_Controller {
 		echo json_encode(array('message' => 'OK'));
 		return;
 	}
+
+	/*
+	 *  Function is used for dupe-checking in contestinglogging
+	 */
+	public function checkIfWorkedBefore() {
+		$call = $this->input->post('call');
+		$band = $this->input->post('band');
+		$mode = $this->input->post('mode');
+		$contest = $this->input->post('contest');
+		$qso = $this->input->post('qso');
+
+		$this->load->model('Contesting_model');
+		$result = $this->Contesting_model->checkIfWorkedBefore($call, $band, $mode, $contest, $qso);
+		
+		header('Content-Type: application/json');
+		if ($result->num_rows()) {
+			echo json_encode(array('message' => 'Worked before'));
+		}
+		return;
+	}
 }
diff --git a/application/models/Contesting_model.php b/application/models/Contesting_model.php
index b026e759..2486b7bd 100644
--- a/application/models/Contesting_model.php
+++ b/application/models/Contesting_model.php
@@ -142,4 +142,28 @@ class Contesting_model extends CI_Model {
 
 		return true;
 	}
+
+	function checkIfWorkedBefore($call, $band, $mode, $contest, $qso) {
+		$CI =& get_instance();
+		$CI->load->model('Stations');
+		$station_id = $CI->Stations->find_active();
+
+		$qsoarray = explode(',', $qso);
+
+        $date = DateTime::createFromFormat('d-m-Y H:i:s', $qsoarray[0]);
+        $date = $date->format('Y-m-d H:i:s');
+
+		$this->db->where('STATION_ID', $station_id);
+		$this->db->where('COL_CALL', xss_clean($call));
+	    $this->db->where("COL_BAND", xss_clean($band));
+		$this->db->where("COL_CONTEST_ID", xss_clean($contest));
+		$this->db->where("COL_TIME_ON >=", $date);
+	    $this->db->group_start();
+		$this->db->where("COL_MODE", xss_clean($mode));
+	    $this->db->or_where("COL_SUBMODE", xss_clean($mode));
+		$this->db->group_end();
+	    $query = $this->db->get($this->config->item('table_name'));
+
+	    return $query;
+	}
 }
diff --git a/application/views/contesting/index.php b/application/views/contesting/index.php
index 599658ed..d875b0d0 100644
--- a/application/views/contesting/index.php
+++ b/application/views/contesting/index.php
@@ -113,6 +113,7 @@
                             <div class="form-group col-md-3">
                                 <label for="callsign"><?php echo $this->lang->line('gen_hamradio_callsign'); ?></label>
                                 <input type="text" class="form-control form-control-sm" id="callsign" name="callsign" required>
+                                <small id="callsign_info" class="badge badge-danger"></small>
                             </div>
 
                             <div class="form-group col-md-1">
diff --git a/assets/js/sections/contesting.js b/assets/js/sections/contesting.js
index 8f6086d9..c6afd092 100644
--- a/assets/js/sections/contesting.js
+++ b/assets/js/sections/contesting.js
@@ -165,12 +165,33 @@ $("#callsign").keyup(function () {
 			$('.callsign-suggestions').text(result);
 			highlight(call.toUpperCase());
 		});
+		checkIfWorkedBefore();
 	}
 	else if (call.length <= 2) {
 		$('.callsign-suggestions').text("");
 	}
 });
 
+function checkIfWorkedBefore() {
+	$('#callsign_info').text("");
+	$.ajax({
+		url: base_url + 'index.php/contesting/checkIfWorkedBefore',
+		type: 'post',
+		data: {
+			'call': $("#callsign").val(),
+			'mode': $("#mode").val(),
+			'band': $("#band").val(),
+			'contest': $("#contestname").val(),
+			'qso': localStorage.getItem("qso")
+		},
+		success: function (result) {
+			if (result.message == 'Worked before') {
+				$('#callsign_info').text("Worked before!");
+			}
+		}
+	});
+}
+
 function reset_log_fields() {
 	$('#name').val("");
 	$('.callsign-suggestions').text("");
@@ -181,6 +202,7 @@ function reset_log_fields() {
 	$('#exch_gridsquare_r').val("");
 	$("#callsign").focus();
 	setRst($("#mode").val());
+	$('#callsign_info').text("");
 }
 
 RegExp.escape = function (text) {
@@ -218,6 +240,7 @@ $('#mode').change(function () {
 		$('#frequency_rx').val("");
 	});
 	setRst($("#mode").val());
+	checkIfWorkedBefore();
 });
 
 /* Calculate Frequency */
@@ -227,6 +250,7 @@ $('#band').change(function () {
 		$('#frequency').val(result);
 		$('#frequency_rx').val("");
 	});
+	checkIfWorkedBefore();
 });
 
 $('#exchangetype').change(function () {