diff --git a/configs/config.example.yml b/configs/config.example.yml
index 7609de15..0ac084d6 100644
--- a/configs/config.example.yml
+++ b/configs/config.example.yml
@@ -225,6 +225,8 @@ protocols:
         legacyGroupReg: false
         # Flag indicating the host should send a network grant demand TDU for conventional traffic.
         convNetGrantDemand: false
+        # Flag indicating the host should demand a full unit registration for a refused affiliation request.
+        demandUnitRegForRefusedAff: true
         # Flag indicating the host should verify group affiliation.
         verifyAff: false
         # Flag indicating the host should verify unit registration.
diff --git a/src/host/p25/Control.cpp b/src/host/p25/Control.cpp
index 4efa443f..d55b9996 100644
--- a/src/host/p25/Control.cpp
+++ b/src/host/p25/Control.cpp
@@ -5,7 +5,7 @@
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  *  Copyright (C) 2016,2017,2018 Jonathan Naylor, G4KLX
- *  Copyright (C) 2017-2024 Bryan Biedenkapp, N2PLL
+ *  Copyright (C) 2017-2025 Bryan Biedenkapp, N2PLL
  *
  */
 #include "Defines.h"
@@ -78,6 +78,7 @@ Control::Control(bool authoritative, uint32_t nac, uint32_t callHang, uint32_t q
     m_convNetGrantDemand(false),
     m_sndcpSupport(false),
     m_ignoreAffiliationCheck(false),
+    m_demandUnitRegForRefusedAff(true),
     m_idenTable(idenTable),
     m_ridLookup(ridLookup),
     m_tidLookup(tidLookup),
@@ -267,6 +268,7 @@ void Control::setOptions(yaml::Node& conf, bool supervisor, const std::string cw
     m_sndcpSupport = p25Protocol["sndcpSupport"].as<bool>(false);
 
     m_ignoreAffiliationCheck = p25Protocol["ignoreAffiliationCheck"].as<bool>(false);
+    m_demandUnitRegForRefusedAff = p25Protocol["demandUnitRegForRefusedAff"].as<bool>(true);
 
     yaml::Node control = p25Protocol["control"];
     m_enableControl = control["enable"].as<bool>(false);
@@ -488,6 +490,7 @@ void Control::setOptions(yaml::Node& conf, bool supervisor, const std::string cw
         LogInfo("    Unit-to-Unit Availability Check: %s", m_control->m_unitToUnitAvailCheck ? "yes" : "no");
         LogInfo("    Explicit Source ID Support: %s", m_allowExplicitSourceId ? "yes" : "no");
         LogInfo("    Conventional Network Grant Demand: %s", m_convNetGrantDemand ? "yes" : "no");
+        LogInfo("    Demand Unit Registration for Refused Affiliation: %s", m_demandUnitRegForRefusedAff ? "yes" : "no");
 
         if (disableUnitRegTimeout) {
             LogInfo("    Disable Unit Registration Timeout: yes");
diff --git a/src/host/p25/Control.h b/src/host/p25/Control.h
index f81ead09..59cccbe2 100644
--- a/src/host/p25/Control.h
+++ b/src/host/p25/Control.h
@@ -5,7 +5,7 @@
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  *  Copyright (C) 2016,2017 Jonathan Naylor, G4KLX
- *  Copyright (C) 2017-2024 Bryan Biedenkapp, N2PLL
+ *  Copyright (C) 2017-2025 Bryan Biedenkapp, N2PLL
  *
  */
 /**
@@ -308,6 +308,7 @@ namespace p25
         bool m_convNetGrantDemand;
         bool m_sndcpSupport;
         bool m_ignoreAffiliationCheck;
+        bool m_demandUnitRegForRefusedAff;
 
         ::lookups::IdenTableLookup* m_idenTable;
         ::lookups::RadioIdLookup* m_ridLookup;
diff --git a/src/host/p25/packet/ControlSignaling.cpp b/src/host/p25/packet/ControlSignaling.cpp
index 80947a0e..1e9f36f2 100644
--- a/src/host/p25/packet/ControlSignaling.cpp
+++ b/src/host/p25/packet/ControlSignaling.cpp
@@ -4,7 +4,7 @@
  * GPLv2 Open Source. Use is subject to license terms.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
- *  Copyright (C) 2017-2024 Bryan Biedenkapp, N2PLL
+ *  Copyright (C) 2017-2025 Bryan Biedenkapp, N2PLL
  *  Copyright (C) 2022 Jason-UWU
  *
  */
@@ -540,7 +540,11 @@ bool ControlSignaling::process(uint8_t* data, uint32_t len, std::unique_ptr<lc::
                     writeRF_TSDU_ACK_FNE(srcId, TSBKO::IOSP_GRP_AFF, true, true);
                 }
 
-                writeRF_TSDU_Grp_Aff_Rsp(srcId, dstId);
+                if (writeRF_TSDU_Grp_Aff_Rsp(srcId, dstId) == ResponseCode::REFUSED) {
+                    if (m_p25->m_demandUnitRegForRefusedAff) {
+                        writeRF_TSDU_U_Reg_Cmd(srcId);
+                    }
+                }
             }
             break;
             case TSBKO::ISP_GRP_AFF_Q_RSP:
@@ -2637,10 +2641,8 @@ void ControlSignaling::writeRF_TSDU_Deny(uint32_t srcId, uint32_t dstId, uint8_t
 
 /* Helper to write a group affiliation response packet. */
 
-bool ControlSignaling::writeRF_TSDU_Grp_Aff_Rsp(uint32_t srcId, uint32_t dstId)
+uint8_t ControlSignaling::writeRF_TSDU_Grp_Aff_Rsp(uint32_t srcId, uint32_t dstId)
 {
-    bool ret = false;
-
     std::unique_ptr<IOSP_GRP_AFF> iosp = std::make_unique<IOSP_GRP_AFF>();
     iosp->setMFId(m_lastMFID);
     iosp->setAnnounceGroup(m_announcementGroup);
@@ -2714,7 +2716,6 @@ bool ControlSignaling::writeRF_TSDU_Grp_Aff_Rsp(uint32_t srcId, uint32_t dstId)
         }
 
         ::ActivityLog("P25", true, "group affiliation request from %u to %s %u", srcId, "TG ", dstId);
-        ret = true;
 
         // update dynamic affiliation table
         m_p25->m_affiliations.groupAff(srcId, dstId);
@@ -2724,7 +2725,7 @@ bool ControlSignaling::writeRF_TSDU_Grp_Aff_Rsp(uint32_t srcId, uint32_t dstId)
     }
 
     writeRF_TSDU_SBF_Imm(iosp.get(), noNet);
-    return ret;
+    return iosp->getResponse();
 }
 
 /* Helper to write a unit registration response packet. */
diff --git a/src/host/p25/packet/ControlSignaling.h b/src/host/p25/packet/ControlSignaling.h
index 62815caa..ce19d6ca 100644
--- a/src/host/p25/packet/ControlSignaling.h
+++ b/src/host/p25/packet/ControlSignaling.h
@@ -4,7 +4,7 @@
  * GPLv2 Open Source. Use is subject to license terms.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
- *  Copyright (C) 2017-2024 Bryan Biedenkapp, N2PLL
+ *  Copyright (C) 2017-2025 Bryan Biedenkapp, N2PLL
  *
  */
 /**
@@ -364,8 +364,9 @@ namespace p25
              * @brief Helper to write a group affiliation response packet.
              * @param srcId Source Radio ID.
              * @param dstId Destination ID.
+             * @returns uint8_t Grant response code.
              */
-            bool writeRF_TSDU_Grp_Aff_Rsp(uint32_t srcId, uint32_t dstId);
+            uint8_t writeRF_TSDU_Grp_Aff_Rsp(uint32_t srcId, uint32_t dstId);
             /**
              * @brief Helper to write a unit registration response packet.
              * @param srcId Source Radio ID.
diff --git a/src/host/p25/packet/Voice.cpp b/src/host/p25/packet/Voice.cpp
index 56f763ff..c1bba2d3 100644
--- a/src/host/p25/packet/Voice.cpp
+++ b/src/host/p25/packet/Voice.cpp
@@ -409,7 +409,7 @@ bool Voice::process(uint8_t* data, uint32_t len)
                         // are we auto-registering legacy radios to groups?
                         if (m_p25->m_legacyGroupReg && group) {
                             if (!m_p25->m_affiliations.isGroupAff(srcId, dstId)) {
-                                if (!m_p25->m_control->writeRF_TSDU_Grp_Aff_Rsp(srcId, dstId)) {
+                                if (m_p25->m_control->writeRF_TSDU_Grp_Aff_Rsp(srcId, dstId) != ResponseCode::ACCEPT) {
                                     LogWarning(LOG_RF, P25_HDU_STR " denial, conventional affiliation required, not affiliated to TGID, srcId = %u, dstId = %u", srcId, dstId);
                                     m_p25->m_rfLastDstId = 0U;
                                     m_p25->m_rfLastSrcId = 0U;