If you find that there are other characters as well, which is fairly common, you can sort it out this way:
whileprintingrecords;
stringvar currphone:= trim({table.phone});
stringvar Phone:="";
numbervar counter;
For counter := 1 to len(currphone) do(
if isnumeric(mid(currphone,counter,1)) then
Phone:=Phone + mid(currphone,counter,1)
);
if len(phone) <> 10 then
"*" & Phone
else
Phone
This will also flag bad phone number lengths with an asterisk if it isn't 10 characters.
-k