diff --git a/libs/freetdm/src/isdn/Q931.c b/libs/freetdm/src/isdn/Q931.c
index 6c0b65613c..e1606b0809 100644
--- a/libs/freetdm/src/isdn/Q931.c
+++ b/libs/freetdm/src/isdn/Q931.c
@@ -329,6 +329,7 @@ L3INT Q931Rx23(Q931_TrunkInfo_t *pTrunk, L3UCHAR * buf, L3INT Size)
     m->ProtDisc = Mes[IOff++];
 
     /* CRV */
+	m->CRVFlag = Mes[IOff + 1] & 0x80;
     m->CRV = Q931Uie_CRV(pTrunk, Mes, m->buf, &IOff, &ISize);
 
     /* Message Type */
diff --git a/libs/freetdm/src/isdn/Q931ie.c b/libs/freetdm/src/isdn/Q931ie.c
index f3041b2b0e..ca3bb9640b 100644
--- a/libs/freetdm/src/isdn/Q931ie.c
+++ b/libs/freetdm/src/isdn/Q931ie.c
@@ -1307,12 +1307,12 @@ L3USHORT Q931Uie_CRV(Q931_TrunkInfo_t *pTrunk, L3UCHAR *IBuf, L3UCHAR *OBuf, L3I
 
     if(l == 1) /* One octet CRV */
     {
-        CRV = IBuf[Octet];
+        CRV = IBuf[Octet] & 0x7F;
         Octet++;
     }
     else if(l==2) /* two octet CRV */
     {
-        CRV = IBuf[Octet] << 8;
+        CRV = (IBuf[Octet] << 8) & 0x7F;
         CRV = CRV + IBuf[Octet+1];
         Octet += 2;
     }
diff --git a/libs/freetdm/src/isdn/Q931mes.c b/libs/freetdm/src/isdn/Q931mes.c
index bc2facd7cb..d4229fe958 100644
--- a/libs/freetdm/src/isdn/Q931mes.c
+++ b/libs/freetdm/src/isdn/Q931mes.c
@@ -92,7 +92,7 @@ L3INT Q931Pmes_Alerting(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3INT I
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -180,7 +180,7 @@ L3INT Q931Pmes_CallProceeding(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -299,7 +299,7 @@ L3INT Q931Pmes_Connect(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3INT IS
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -395,7 +395,7 @@ L3INT Q931Pmes_ConnectAck(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3INT
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -460,7 +460,7 @@ L3INT Q931Pmes_Disconnect(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3INT
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -535,7 +535,7 @@ L3INT Q931Pmes_Information(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3IN
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -610,7 +610,7 @@ L3INT Q931Pmes_Notify(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3INT ISi
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -678,7 +678,7 @@ L3INT Q931Pmes_Progress(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3INT I
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -756,7 +756,7 @@ L3INT Q931Pmes_Release(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3INT IS
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -823,7 +823,7 @@ L3INT Q931Pmes_ReleaseComplete(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf,
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -890,7 +890,7 @@ L3INT Q931Pmes_Restart(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3INT IS
 
     OBuf[Octet++]    = pMes->ProtDisc;        /* Protocol discriminator        */
     OBuf[Octet++]    = 2;                    /* length is 2 octets            */
-    OBuf[Octet++]    = (L3UCHAR)(pMes->CRV>>8);    /* msb                            */
+    OBuf[Octet++]    = (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);    /* msb                            */
     OBuf[Octet++]    = (L3UCHAR)(pMes->CRV);    /* lsb                            */
     OBuf[Octet++]    = pMes->MesType;        /* message header                */
     
@@ -957,7 +957,7 @@ L3INT Q931Pmes_RestartAck(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3INT
 
     OBuf[Octet++]    = pMes->ProtDisc;        /* Protocol discriminator        */
     OBuf[Octet++]    = 2;                    /* length is 2 octets            */
-    OBuf[Octet++]    = (L3UCHAR)(pMes->CRV>>8);    /* msb                            */
+    OBuf[Octet++]    = (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);    /* msb                            */
     OBuf[Octet++]    = (L3UCHAR)(pMes->CRV);    /* lsb                            */
     OBuf[Octet++]    = pMes->MesType;        /* message header                */
     
@@ -1022,7 +1022,7 @@ L3INT Q931Pmes_Resume(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3INT ISi
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -1081,7 +1081,7 @@ L3INT Q931Pmes_ResumeAck(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3INT
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -1143,7 +1143,7 @@ L3INT Q931Pmes_ResumeReject(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3I
 	/* Q931 Message Header	*/
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb						*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb						*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 
@@ -1258,7 +1258,7 @@ L3INT Q931Pmes_Setup(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3INT ISiz
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb						*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb						*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -1406,7 +1406,7 @@ L3INT Q931Pmes_SetupAck(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3INT I
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -1481,7 +1481,7 @@ L3INT Q931Pmes_Status(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3INT ISi
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -1546,7 +1546,7 @@ L3INT Q931Pmes_StatusEnquiry(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -1603,7 +1603,7 @@ L3INT Q931Pmes_Suspend(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3INT IS
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -1661,7 +1661,7 @@ L3INT Q931Pmes_SuspendAck(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3INT
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
@@ -1719,7 +1719,7 @@ L3INT Q931Pmes_SuspendReject(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb							*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb							*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/
 	
diff --git a/libs/freetdm/src/isdn/include/Q931.h b/libs/freetdm/src/isdn/include/Q931.h
index b0bb3f4275..1243c5a114 100644
--- a/libs/freetdm/src/isdn/include/Q931.h
+++ b/libs/freetdm/src/isdn/include/Q931.h
@@ -390,6 +390,7 @@ typedef struct
     L3UINT			Size;           /* Size of message in bytes             */
     L3UCHAR         ProtDisc;       /* Protocol Discriminator               */
     L3UCHAR         MesType;        /* Message type                         */
+    L3UCHAR         CRVFlag;        /* Call reference value flag            */
     L3INT           CRV;            /* Call reference value                 */
 }Q931mes_Header;
 
@@ -406,6 +407,7 @@ typedef struct
     L3UINT			Size;           /* Size of message in bytes             */
     L3UCHAR         ProtDisc;       /* Protocol Discriminator               */
     L3UCHAR         MesType;        /* Message type                         */
+    L3UCHAR         CRVFlag;        /* Call reference value flag            */
     L3INT           CRV;            /* Call reference value                 */
 
     ie              Shift;
diff --git a/libs/freetdm/src/isdn/nationalmes.c b/libs/freetdm/src/isdn/nationalmes.c
index 41de1531c6..7dc73989e4 100644
--- a/libs/freetdm/src/isdn/nationalmes.c
+++ b/libs/freetdm/src/isdn/nationalmes.c
@@ -158,7 +158,7 @@ L3INT nationalPmes_Setup(Q931_TrunkInfo_t *pTrunk, Q931mes_Generic *IBuf, L3INT
 
 	OBuf[Octet++]	= pMes->ProtDisc;		/* Protocol discriminator		*/
 	OBuf[Octet++]	= 2;					/* length is 2 octets			*/
-	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8);	/* msb						*/
+	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV>>8) | (pMes->CRVFlag << 7);	/* msb						*/
 	OBuf[Octet++]	= (L3UCHAR)(pMes->CRV);	/* lsb							*/
 	OBuf[Octet++]	= pMes->MesType;		/* message header				*/