diff --git a/DMRCSBK.cpp b/DMRCSBK.cpp
index 464b333..5d69043 100644
--- a/DMRCSBK.cpp
+++ b/DMRCSBK.cpp
@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2015,2016 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2015,2016,2020 by Jonathan Naylor G4KLX
  *   Copyright (C) 2019 by Patrick Maier DK5MP
  *
  *   This program is free software; you can redistribute it and/or modify
@@ -111,6 +111,24 @@ bool CDMRCSBK::put(const unsigned char* bytes)
 		CUtils::dump(1U, "Negative Acknowledge Response CSBK", m_data, 12U);
 		break;
 
+	case CSBKO_CALL_ALERT:
+		m_GI    = false;
+		m_dstId = m_data[4U] << 16 | m_data[5U] << 8 | m_data[6U];
+		m_srcId = m_data[7U] << 16 | m_data[8U] << 8 | m_data[9U];
+		m_dataContent = false;
+		m_CBF   = 0U;
+		CUtils::dump(1U, "Call Alert CSBK", m_data, 12U);
+		break;
+
+	case CSBKO_CALL_ALERT_ACK:
+		m_GI    = false;
+		m_dstId = m_data[4U] << 16 | m_data[5U] << 8 | m_data[6U];
+		m_srcId = m_data[7U] << 16 | m_data[8U] << 8 | m_data[9U];
+		m_dataContent = false;
+		m_CBF   = 0U;
+		CUtils::dump(1U, "Call Alert Ack CSBK", m_data, 12U);
+		break;
+
 	default:
 		m_GI    = false;
 		m_srcId = 0U;
diff --git a/DMRCSBK.h b/DMRCSBK.h
index 914b44d..6d5b206 100644
--- a/DMRCSBK.h
+++ b/DMRCSBK.h
@@ -22,13 +22,15 @@
 #include "DMRDefines.h"
 
 enum CSBKO {
-	CSBKO_NONE     = 0x00,
-	CSBKO_UUVREQ   = 0x04,
-	CSBKO_UUANSRSP = 0x05,
-	CSBKO_CTCSBK   = 0x07,
-	CSBKO_NACKRSP  = 0x26,
-	CSBKO_BSDWNACT = 0x38,
-	CSBKO_PRECCSBK = 0x3D
+	CSBKO_NONE           = 0x00,
+	CSBKO_UUVREQ         = 0x04,
+	CSBKO_UUANSRSP       = 0x05,
+	CSBKO_CTCSBK         = 0x07,
+	CSBKO_CALL_ALERT     = 0x1F,
+	CSBKO_CALL_ALERT_ACK = 0x20,
+	CSBKO_NACKRSP        = 0x26,
+	CSBKO_BSDWNACT       = 0x38,
+	CSBKO_PRECCSBK       = 0x3D
 };
 
 class CDMRCSBK
diff --git a/DMRSlot.cpp b/DMRSlot.cpp
index 8ebbce4..f42def4 100644
--- a/DMRSlot.cpp
+++ b/DMRSlot.cpp
@@ -488,6 +488,12 @@ bool CDMRSlot::writeModem(unsigned char *data, unsigned int len)
 			case CSBKO_PRECCSBK:
 				LogMessage("DMR Slot %u, received RF %s Preamble CSBK (%u to follow) from %s to %s%s", m_slotNo, csbk.getDataContent() ? "Data" : "CSBK", csbk.getCBF(), src.c_str(), gi ? "TG ": "", dst.c_str());
 				break;
+			case CSBKO_CALL_ALERT:
+				LogMessage("DMR Slot %u, received RF Call Alert CSBK from %s to %s%s", m_slotNo, src.c_str(), gi ? "TG " : "", dst.c_str());
+				break;
+			case CSBKO_CALL_ALERT_ACK:
+				LogMessage("DMR Slot %u, received RF Call Alert Ack CSBK from %s to %s%s", m_slotNo, src.c_str(), gi ? "TG " : "", dst.c_str());
+				break;
 			default:
 				LogWarning("DMR Slot %u, unhandled RF CSBK type - 0x%02X", m_slotNo, csbko);
 				break;
@@ -1641,6 +1647,12 @@ void CDMRSlot::writeNetwork(const CDMRData& dmrData)
 		case CSBKO_PRECCSBK:
 			LogMessage("DMR Slot %u, received network %s Preamble CSBK (%u to follow) from %s to %s%s", m_slotNo, csbk.getDataContent() ? "Data" : "CSBK", csbk.getCBF(), src.c_str(), gi ? "TG " : "", dst.c_str());
 			break;
+		case CSBKO_CALL_ALERT:
+			LogMessage("DMR Slot %u, received network Call Alert CSBK from %s to %s%s", m_slotNo, src.c_str(), gi ? "TG " : "", dst.c_str());
+			break;
+		case CSBKO_CALL_ALERT_ACK:
+			LogMessage("DMR Slot %u, received network Call Alert Ack CSBK from %s to %s%s", m_slotNo, src.c_str(), gi ? "TG " : "", dst.c_str());
+			break;
 		default:
 			LogWarning("DMR Slot %u, unhandled network CSBK type - 0x%02X", m_slotNo, csbko);
 			break;