diff --git a/p25/Control.cpp b/p25/Control.cpp
index 855c4932..b1667cef 100644
--- a/p25/Control.cpp
+++ b/p25/Control.cpp
@@ -834,23 +834,31 @@ void Control::writeRF_Nulls()
 /// <summary>
 /// Helper to write TDU preamble packet burst.
 /// </summary>
-void Control::writeRF_Preamble()
+/// <param name="preambleCount"></param>
+/// <param name="force"></param>
+void Control::writeRF_Preamble(uint32_t preambleCount, bool force)
 {
-    if (m_modem->hasTX() || m_tduPreambleCount == 0U) {
-        return;
+    if (preambleCount == 0) {
+        preambleCount = m_tduPreambleCount;
     }
 
-    if (m_ccRunning) {
-        return;
+    if (!force) {
+        if (m_modem->hasTX() || m_tduPreambleCount == 0U) {
+            return;
+        }
+
+        if (m_ccRunning) {
+            return;
+        }
     }
 
     if (m_tduPreambleCount > MAX_PREAMBLE_TDU_CNT) {
         LogWarning(LOG_P25, "oversized TDU preamble count, reducing to maximum %u", MAX_PREAMBLE_TDU_CNT);
-        m_tduPreambleCount = MAX_PREAMBLE_TDU_CNT;
+        preambleCount = m_tduPreambleCount = MAX_PREAMBLE_TDU_CNT;
     }
 
     // write TDUs if requested
-    for (uint8_t i = 0U; i < m_tduPreambleCount; i++) {
+    for (uint8_t i = 0U; i < preambleCount; i++) {
         writeRF_TDU(true);
     }
 }
diff --git a/p25/Control.h b/p25/Control.h
index 8a82a79e..edbb6068 100644
--- a/p25/Control.h
+++ b/p25/Control.h
@@ -189,7 +189,7 @@ namespace p25
         /// <summary>Helper to write data nulls.</summary>
         void writeRF_Nulls();
         /// <summary>Helper to write TDU preamble packet burst.</summary>
-        void writeRF_Preamble();
+        void writeRF_Preamble(uint32_t preambleCount = 0, bool force = false);
         /// <summary>Helper to write a P25 TDU packet.</summary>
         void writeRF_TDU(bool noNetwork);
 
diff --git a/p25/TrunkPacket.cpp b/p25/TrunkPacket.cpp
index 4ce51a1c..f76d5179 100644
--- a/p25/TrunkPacket.cpp
+++ b/p25/TrunkPacket.cpp
@@ -213,7 +213,7 @@ bool TrunkPacket::process(uint8_t* data, uint32_t len)
                     LogMessage(LOG_RF, P25_TSDU_STR ", TSBK_IOSP_GRP_VCH (Group Voice Channel Request), srcId = %u, dstId = %u", srcId, dstId);
                 }
 
-                writeRF_TSDU_Grant(true, false, false);
+                writeRF_TSDU_Grant(true);
                 break;
             case TSBK_IOSP_UU_VCH:
                 // make sure control data is supported
@@ -236,7 +236,7 @@ bool TrunkPacket::process(uint8_t* data, uint32_t len)
                     writeRF_TSDU_UU_Ans_Req(srcId, dstId);
                 }
                 else {
-                    writeRF_TSDU_Grant(false, false, false);
+                    writeRF_TSDU_Grant(false);
                 }
                 break;
             case TSBK_IOSP_UU_ANS:
@@ -259,7 +259,7 @@ bool TrunkPacket::process(uint8_t* data, uint32_t len)
                         writeRF_TSDU_ACK_FNE(dstId, TSBK_IOSP_UU_ANS, false, true);
                     }
 
-                    writeRF_TSDU_Grant(false, false, false);
+                    writeRF_TSDU_Grant(false);
                 }
                 else if (m_rfTSBK.getResponse() == P25_ANS_RSP_DENY) {
                     writeRF_TSDU_Deny(P25_DENY_RSN_TGT_UNIT_REFUSED, TSBK_IOSP_UU_ANS);
@@ -1465,7 +1465,8 @@ void TrunkPacket::writeRF_TDULC_ChanRelease(bool grp, uint32_t srcId, uint32_t d
 /// </summary>
 /// <param name="noNetwork"></param>
 /// <param name="clearBeforeWrite"></param>
-void TrunkPacket::writeRF_TSDU_SBF(bool noNetwork, bool clearBeforeWrite)
+/// <param name="force"></param>
+void TrunkPacket::writeRF_TSDU_SBF(bool noNetwork, bool clearBeforeWrite, bool force)
 {
     if (!m_p25->m_control)
         return;
@@ -1496,19 +1497,21 @@ void TrunkPacket::writeRF_TSDU_SBF(bool noNetwork, bool clearBeforeWrite)
     if (!noNetwork)
         writeNetworkRF(data + 2U, true);
 
-    if (m_p25->m_dedicatedControl && m_ctrlTSDUMBF) {
-        writeRF_TSDU_MBF(clearBeforeWrite);
-        return;
-    }
+    if (!force) {
+        if (m_p25->m_dedicatedControl && m_ctrlTSDUMBF) {
+            writeRF_TSDU_MBF(clearBeforeWrite);
+            return;
+        }
 
-    if (m_p25->m_ccRunning && m_ctrlTSDUMBF) {
-        writeRF_TSDU_MBF(clearBeforeWrite);
-        return;
-    }
+        if (m_p25->m_ccRunning && m_ctrlTSDUMBF) {
+            writeRF_TSDU_MBF(clearBeforeWrite);
+            return;
+        }
 
-    if (clearBeforeWrite) {
-        m_p25->m_modem->clearP25Data();
-        m_p25->m_queue.clear();
+        if (clearBeforeWrite) {
+            m_p25->m_modem->clearP25Data();
+            m_p25->m_queue.clear();
+        }
     }
 
     if (m_p25->m_duplex) {
@@ -1985,7 +1988,7 @@ bool TrunkPacket::writeRF_TSDU_Grant(bool grp, bool skip, bool net)
 
         // transmit group grant
         m_rfTSBK.setLCO(TSBK_IOSP_GRP_VCH);
-        writeRF_TSDU_SBF(false, true);
+        writeRF_TSDU_SBF(false, true, net);
     }
     else {
         if (!net) {
@@ -1999,7 +2002,7 @@ bool TrunkPacket::writeRF_TSDU_Grant(bool grp, bool skip, bool net)
 
         // transmit private grant
         m_rfTSBK.setLCO(TSBK_IOSP_UU_VCH);
-        writeRF_TSDU_SBF(false, true);
+        writeRF_TSDU_SBF(false, true, net);
     }
 
     m_rfTSBK.setLCO(lco);
diff --git a/p25/TrunkPacket.h b/p25/TrunkPacket.h
index 5b9a6182..aa8ac381 100644
--- a/p25/TrunkPacket.h
+++ b/p25/TrunkPacket.h
@@ -175,7 +175,7 @@ namespace p25
         void writeRF_TDULC_ChanRelease(bool grp, uint32_t srcId, uint32_t dstId);
 
         /// <summary>Helper to write a single-block P25 TSDU packet.</summary>
-        void writeRF_TSDU_SBF(bool noNetwork, bool clearBeforeWrite = false);
+        void writeRF_TSDU_SBF(bool noNetwork, bool clearBeforeWrite = false, bool force = false);
         /// <summary>Helper to write a multi-block (3-block) P25 TSDU packet.</summary>
         void writeRF_TSDU_MBF(bool clearBeforeWrite = false);
 
@@ -183,7 +183,7 @@ namespace p25
         void queueRF_TSBK_Ctrl(uint8_t lco);
 
         /// <summary>Helper to write a grant packet.</summary>
-        bool writeRF_TSDU_Grant(bool grp, bool skip, bool net);
+        bool writeRF_TSDU_Grant(bool grp, bool skip = false, bool net = false);
         /// <summary>Helper to write a unit to unit answer request packet.</summary>
         void writeRF_TSDU_UU_Ans_Req(uint32_t srcId, uint32_t dstId);
         /// <summary>Helper to write a acknowledge packet.</summary>
diff --git a/p25/VoicePacket.cpp b/p25/VoicePacket.cpp
index 6f806622..507d5d6c 100644
--- a/p25/VoicePacket.cpp
+++ b/p25/VoicePacket.cpp
@@ -343,7 +343,7 @@ bool VoicePacket::process(uint8_t* data, uint32_t len)
                             }
                         }                        
 
-                        if (!m_p25->m_trunk->writeRF_TSDU_Grant(group, false, false)) {
+                        if (!m_p25->m_trunk->writeRF_TSDU_Grant(group)) {
                             return false;
                         }
                     }
@@ -356,7 +356,7 @@ bool VoicePacket::process(uint8_t* data, uint32_t len)
             // single-channel trunking or voice on control support?
             if (m_p25->m_control && m_p25->m_voiceOnControl) {
                 m_p25->m_ccRunning = false; // otherwise the grant will be bundled with other packets
-                m_p25->m_trunk->writeRF_TSDU_Grant(group, true, false);
+                m_p25->m_trunk->writeRF_TSDU_Grant(group, true);
             }
 
             m_hadVoice = true;
@@ -779,6 +779,16 @@ bool VoicePacket::processNetwork(uint8_t* data, uint32_t len, lc::LC& control, d
                 count += 16U;
 
                 if (m_p25->m_netState == RS_NET_IDLE) {
+                    // are we interrupting a running CC?
+                    if (m_p25->m_ccRunning) {
+                        g_interruptP25Control = true;
+                    }
+
+                    // single-channel trunking or voice on control support?
+                    if (m_p25->m_control && m_p25->m_voiceOnControl) {
+                        m_p25->m_ccRunning = false; // otherwise the grant will be bundled with other packets
+                    }
+
                     m_p25->m_modem->clearP25Data();
                     m_p25->m_queue.clear();
                     
@@ -1191,7 +1201,7 @@ void VoicePacket::writeNet_LDU1(const lc::LC& control, const data::LowSpeedData&
         // single-channel trunking or voice on control support?
         if (m_p25->m_control && m_p25->m_voiceOnControl) {
             m_p25->m_ccRunning = false; // otherwise the grant will be bundled with other packets
-            if (!m_p25->m_trunk->writeRF_TSDU_Grant(group, true, true)) {
+            if (!m_p25->m_trunk->writeRF_TSDU_Grant(group, false, true)) {
                 if (m_network != NULL)
                     m_network->resetP25();
 
@@ -1213,6 +1223,8 @@ void VoicePacket::writeNet_LDU1(const lc::LC& control, const data::LowSpeedData&
 
                 return;
             }
+
+            m_p25->writeRF_Preamble(0, true);
         }
 
         m_hadVoice = true;