It is hard to determine a person that has a number tied to their name, unless you know what the numbers stand for. The numbers 123456789 could be an id number for someone in the government or a persons id number in witness protection.
If the numbers are not allowed to repeat themselves then 362,880. * * * * * That is the number of permutations, not combinations. In a combination the order of the digits does not matter. So there is only one 9-digit combination.