be more flexible in what we accept for char based dtmf (ABCD and abcd), patch from George Shaw. Thanks.

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@4197 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/switch_utils.c

@@ -397,6 +397,7 @@ SWITCH_DECLARE(unsigned char) switch_char_to_rfc2833(char key)
     char *c;
 	unsigned char counter = 0;
 
+    key = (char)toupper(key);
     for (c = RFC2833_CHARS; *c ; c++) {
         if (*c == key) {
             return counter;