--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libcoding/alpha_addr.c	Sun Aug 27 06:43:23 2023 +0000
@@ -0,0 +1,24 @@
+/*
+ * This library module implements encoding of alphanumeric From addresses
+ * that are allowed in SMS-DELIVER TPDUs.
+ */
+
+#include <sys/types.h>
+
+u_char alpha_septets_to_digits[12] = {0, 2, 4, 6, 7, 9, 11, 13, 14, 16, 18, 20};
+
+encode_alpha_addr(arg, bin)
+	char *arg;
+	u_char *bin;
+{
+	u_char gsm7[11];
+	int rc;
+
+	rc = qstring_arg_to_gsm7(arg, gsm7, 11);
+	if (rc < 0)
+		return(rc);
+	bin[0] = alpha_septets_to_digits[rc];
+	bin[1] = 0x50;
+	gsm7_pack(gsm7, bin + 2, (bin[0] + 1) >> 1);
+	return(0);
+}