--- plugins/mm-modem-huawei-gsm.c.orig	2011-11-09 23:54:26.313364125 +0200
+++ plugins/mm-modem-huawei-gsm.c	2011-11-10 00:23:51.668457776 +0200
@@ -888,6 +888,12 @@
 
     *scheme = MM_MODEM_GSM_USSD_SCHEME_7BIT;
     gsm = mm_charset_utf8_to_unpacked_gsm (command, &len);
+    /* if command is a multiple of 7 characters long, pad it */
+    if (len % 7 == 0) {
+        gsm = g_realloc (gsm, len + 1);
+        gsm[len] = 0x0d;
+        len++;
+    }
     packed = gsm_pack (gsm, len, 0, &packed_len);
     hex = utils_bin2hexstr (packed, packed_len);
     g_free (packed);