Have a look at this link.
http://www.scribd.com/doc/238209/LinksysSipura-Dial-Plan-tutorial
You can use an "x" to mean any digit, or you can specify a single digit (that is allowed), or a range of digits.
So |*xxx| would allow any 3 digit star code, or |*7xx| would allow only codes beginning with 7.
Codes are "match attempted" from left to right.