diff --git a/p25/P25Defines.h b/p25/P25Defines.h
index 55a99206..c84b4adb 100644
--- a/p25/P25Defines.h
+++ b/p25/P25Defines.h
@@ -305,7 +305,11 @@ namespace p25
     const uint8_t   TSBK_ISP_U_DEREG_REQ = 0x2BU;       // U DE REG REQ - Unit De-Registration Request
     const uint8_t   TSBK_ISP_LOC_REG_REQ = 0x2DU;       // LOC REG REQ - Location Registration Request
     const uint8_t   TSBK_ISP_STS_Q_REQ = 0x1CU;          // STS_Q_REQ - Status Query Request
+    const uint8_t   TSBK_ISP_AUTH_Q = 0x2EU;            // AUTH_Q - Authentication Query
+    const uint8_t   TSBK_ISP_AUTH_RSP = 0x2FU;           // AUTH_RSP - Authentication Response
 
+
+    
     // TSBK Outbound Signalling Packet (OSP) Opcode(s)
     const uint8_t   TSBK_OSP_GRP_VCH_GRANT_UPD = 0x02U; // GRP VCH GRANT UPD - Group Voice Channel Grant Update
     const uint8_t   TSBK_OSP_UU_VCH_GRANT_UPD = 0x06U;  // UU VCH GRANT UPD - Unit-to-Unit Voice Channel Grant Update
@@ -327,7 +331,8 @@ namespace p25
     const uint8_t   TSBK_OSP_ADJ_STS_BCAST = 0x3CU;     // ADJ STS BCAST - Adjacent Site Status Broadcast
     const uint8_t   TSBK_OSP_IDEN_UP = 0x3DU;           // IDEN UP - Channel Identifier Update
     const uint8_t   TSBK_OSP_STS_Q = 0x1AU;             // STS_Q - Status Query
-
+    const uint8_t   TSBK_OSP_AUTH_CMD = 0x2EU;           // AUTH_CMD - Authentication Command
+    
     // TSBK Motorola Outbound Signalling Packet (OSP) Opcode(s)
     const uint8_t   TSBK_OSP_MOT_GRG_ADD = 0x00U;       // MOT GRG ADD - Motorola / Group Regroup Add (Patch Supergroup)
     const uint8_t   TSBK_OSP_MOT_GRG_DEL = 0x01U;       // MOT GRG DEL - Motorola / Group Regroup Delete (Unpatch Supergroup)