Can anyone show how to populate a ListBox with Callsigns from all rows in a clustered table?

I can create new records in a table with unique Callsigns as the primary key.  I can even access all of the data in a table’s record with a specific Callsign.  But what I do not know how to do is to populate a Listbox with items of all Callsigns from a clustered table in alphabetical order.  Can anyone provide an example of this in the C# language?  Please help.
Maurice