-#define PDU_TYPE 0x11 /* first byte of PDU, SMS submit */
-#define PDU_MR 0x00 /* default message reference, filled by Siemens A1 */
-#define PDU_PID 0x00 /* PDU protocol identifier, SMS message type */
-#define PDU_DCS 0x00 /* PDU Data Coding Scheme, 7-bit class-2 message */
-#define PDU_VP 0xFF /* PDU Validity Period, maximum relative time */