diff --git a/dlls/CMakeLists.txt b/dlls/CMakeLists.txt
index b2b6fc77..1109ea14 100644
--- a/dlls/CMakeLists.txt
+++ b/dlls/CMakeLists.txt
@@ -478,6 +478,7 @@ set(HOOKS_SRC
 	hooks/hlds_hooks.cpp
 	hooks/PluginManager.cpp
 	hooks/rehlds.cpp
+	hooks/rehlds_hooks.cpp
 	../common/rehlds_interface.cpp
 )
 
diff --git a/dlls/game.cpp b/dlls/game.cpp
index 6ed3209c..c330f308 100644
--- a/dlls/game.cpp
+++ b/dlls/game.cpp
@@ -85,6 +85,7 @@ cvar_t* g_psv_allow_autoaim = NULL;
 cvar_t	*g_footsteps = NULL;
 cvar_t	*g_developer = NULL;
 cvar_t	*sv_max_client_edicts = NULL;
+cvar_t	*sv_voiceenable = NULL;
 cvar_t	*sv_stepsize = NULL;
 cvar_t	*sv_lowercase = NULL;
 
@@ -280,6 +281,7 @@ void GameDLLInit( void )
 	g_footsteps = CVAR_GET_POINTER( "mp_footsteps" );
 	g_developer = CVAR_GET_POINTER( "developer" );
 	sv_max_client_edicts = CVAR_GET_POINTER( "sv_max_client_edicts" );
+	sv_voiceenable = CVAR_GET_POINTER( "sv_voiceenable" );
 	sv_stepsize = CVAR_GET_POINTER( "sv_stepsize" );
 	sv_lowercase = CVAR_GET_POINTER( "sv_lowercase" );
 
@@ -342,5 +344,6 @@ void GameDLLInit( void )
 	SERVER_COMMAND( "exec skill.cfg\n" );
 
 	RehldsApi_Init();
+	RegisterRehldsHooks();
 }
 
diff --git a/dlls/game.h b/dlls/game.h
index 2a496603..e59805c7 100644
--- a/dlls/game.h
+++ b/dlls/game.h
@@ -100,6 +100,7 @@ EXPORT extern cvar_t	*g_psv_allow_autoaim;
 EXPORT extern cvar_t	*g_footsteps;
 EXPORT extern cvar_t	*g_developer;
 EXPORT extern cvar_t	*sv_max_client_edicts;
+EXPORT extern cvar_t	*sv_voiceenable;
 EXPORT extern cvar_t	*sv_stepsize;
 EXPORT extern cvar_t	*sv_lowercase;
 
diff --git a/dlls/hooks/PluginHooks.h b/dlls/hooks/PluginHooks.h
index 0b440bd7..89815391 100644
--- a/dlls/hooks/PluginHooks.h
+++ b/dlls/hooks/PluginHooks.h
@@ -130,6 +130,9 @@ struct HLCOOP_PLUGIN_HOOKS {
 
 	// called after client data is updated by the mod and before it is returned to the engine
 	HOOK_RETURN_DATA (*pfnUpdateClientDataPost)(const edict_t* ent, int sendweapons, clientdata_t* cd);
+
+	// called before voice data is sent to a player. Set mute to true to block the message to the receiver
+	HOOK_RETURN_DATA (*pfnSendVoiceData)(int senderidx, int receiveridx, uint8_t* data, int sz, bool& mute);
 };
 
 EXPORT void RegisterPlugin(void* plugin, HLCOOP_PLUGIN_HOOKS* hooks, const char* name);
diff --git a/dlls/hooks/rehlds.h b/dlls/hooks/rehlds.h
index e5026227..2ad9ba58 100644
--- a/dlls/hooks/rehlds.h
+++ b/dlls/hooks/rehlds.h
@@ -30,9 +30,16 @@ typedef struct cache_user_s
 #include "rehlds/public/rehlds/rehlds_api.h"
 
 bool RehldsApi_Init();
+void RegisterRehldsHooks();
+void UnregisterRehldsHooks();
 
 EXPORT extern IRehldsApi* g_RehldsApi;
 EXPORT extern const RehldsFuncs_t* g_RehldsFuncs;
 EXPORT extern IRehldsServerData* g_RehldsData;
 EXPORT extern IRehldsHookchains* g_RehldsHookchains;
-EXPORT extern IRehldsServerStatic* g_RehldsSvs;
\ No newline at end of file
+EXPORT extern IRehldsServerStatic* g_RehldsSvs;
+
+// can send network messages larger than 512 bytes (SVC_VOICEDATA)
+// msgMode = MSG_BROADCAST or MSG_ONE_UNRELIABLE
+// entindex = 1-based player index
+EXPORT void rehlds_SendBigMessage(int msgMode, int msgType, void* data, int sz, int playerindex);
\ No newline at end of file
diff --git a/dlls/hooks/rehlds_hooks.cpp b/dlls/hooks/rehlds_hooks.cpp
new file mode 100644
index 00000000..88e93a11
--- /dev/null
+++ b/dlls/hooks/rehlds_hooks.cpp
@@ -0,0 +1,107 @@
+#include "rehlds.h"
+#include "util.h"
+#include "PluginManager.h"
+
+void rehlds_SendBigMessage_internal(int msgType, void* data, int sz, int playerindex) {
+	IGameClient* dstClient = g_RehldsSvs->GetClient(playerindex - 1);
+	sizebuf_t* dstDatagram = dstClient->GetDatagram();
+
+	if (dstDatagram->cursize + sz + 3 >= dstDatagram->maxsize) {
+		ALERT(at_error, "Message %s too large: %d\n", msgTypeStr(msgType), sz);
+		return;
+	}
+
+	g_RehldsFuncs->MSG_WriteByte(dstDatagram, msgType);
+	g_RehldsFuncs->MSG_WriteBuf(dstDatagram, sz, data);
+}
+
+void rehlds_SendBigMessage(int msgMode, int msgType, void* data, int sz, int playerindex) {
+	if (!g_RehldsFuncs) {
+		ALERT(at_console, "Rehlds API not initialized!\n");
+		return;
+	}
+
+	if (msgMode != MSG_BROADCAST) {
+		if (playerindex > 0 && playerindex <= gpGlobals->maxClients)
+			rehlds_SendBigMessage_internal(msgType, data, sz, playerindex);
+		return;
+	}
+	
+	for (int i = 1; i <= gpGlobals->maxClients; i++) {
+		CBasePlayer* plr = UTIL_PlayerByIndex(i);
+		if (plr)
+			rehlds_SendBigMessage_internal(msgType, data, sz, i);
+	}
+}
+
+void SV_ParseVoiceData_hlcoop(IGameClient* cl) {
+	uint8_t chReceived[4096];
+	unsigned int nDataLength = g_RehldsFuncs->MSG_ReadShort();
+
+	if (nDataLength > sizeof(chReceived)) {
+		g_RehldsFuncs->DropClient(cl, FALSE, "Invalid voice data\n");
+		return;
+	}
+
+	g_RehldsFuncs->MSG_ReadBuf(nDataLength, chReceived);
+
+	if (sv_voiceenable->value == 0.0f)
+		return;
+
+	int sender = cl->GetId();
+	for (int i = 1; i <= gpGlobals->maxClients; i++)
+	{
+		CBasePlayer* plr = UTIL_PlayerByIndex(i);
+
+		if (!plr || !g_engfuncs.pfnVoice_GetClientListening(i, sender+1)) {
+			continue;
+		}
+		
+		bool pluginWantsMute = false;
+
+		CALL_HOOKS_VOID(pfnSendVoiceData, sender + 1, i, chReceived, nDataLength, pluginWantsMute);
+
+		if (pluginWantsMute) {
+			continue;
+		}
+
+		IGameClient* dstClient = g_RehldsSvs->GetClient(i - 1);
+		sizebuf_t* dstDatagram = dstClient->GetDatagram();
+
+		int nSendLength = nDataLength;
+		if (sender + 1 == i && !dstClient->GetLoopback()) // voice_loopback
+			nSendLength = 0;
+		
+		if (dstDatagram->cursize + nSendLength + 6 < dstDatagram->maxsize) {
+			g_RehldsFuncs->MSG_WriteByte(dstDatagram, SVC_VOICEDATA);
+			g_RehldsFuncs->MSG_WriteByte(dstDatagram, sender);
+			g_RehldsFuncs->MSG_WriteShort(dstDatagram, nSendLength);
+			g_RehldsFuncs->MSG_WriteBuf(dstDatagram, nSendLength, chReceived);
+		}
+	}
+}
+
+void Rehlds_HandleNetCommand(IRehldsHook_HandleNetCommand* chain, IGameClient* cl, uint8_t opcode) {
+	const int clc_voicedata = 8;
+
+	if (opcode == clc_voicedata) {
+		SV_ParseVoiceData_hlcoop(cl);
+		return;
+	}
+
+	chain->callNext(cl, opcode);
+}
+
+void RegisterRehldsHooks() {
+	if (!g_RehldsHookchains) {
+		return;
+	}
+	g_RehldsHookchains->HandleNetCommand()->registerHook(&Rehlds_HandleNetCommand, HC_PRIORITY_DEFAULT + 1);
+}
+
+void UnregisterRehldsHooks() {
+	if (!g_RehldsHookchains) {
+		return;
+	}
+	g_RehldsHookchains->HandleNetCommand()->unregisterHook(&Rehlds_HandleNetCommand);
+}
\ No newline at end of file