diff --git a/libs/openzap/src/isdn/Q931.c b/libs/openzap/src/isdn/Q931.c
index 272d768766..0415f39512 100644
--- a/libs/openzap/src/isdn/Q931.c
+++ b/libs/openzap/src/isdn/Q931.c
@@ -340,10 +340,13 @@ L3INT Q931Rx23(Q931_TrunkInfo_t *pTrunk, L3UCHAR * buf, L3INT Size)
 
     L3INT IOff = 0;
 
-    /* Protocol Discriminator */
+	/* Reset our decode buffer */
+	memset(pTrunk->L3Buf, 0, sizeof(pTrunk->L3Buf));
+
+	/* Protocol Discriminator */
     m->ProtDisc = Mes[IOff++];
 
-    /* CRV */
+    /* CRV */add 
     m->CRVFlag = Mes[IOff + 1] & 0x80;
     m->CRV = Q931Uie_CRV(pTrunk, Mes, m->buf, &IOff, &ISize);