1. A computer-implemented method comprising: determining a country of origin of a document by selecting, from a plurality of potential countries, a country associated with the document; processing the document, using the determined country of origin, to determine a numeric or alphanumeric sequence of characters in the document to establish a call by: recalling rules relating to the format of said sequence associated with the determined country of origin of the document; and searching the document to identify a sequence in the document satisfying said format of the determined country of origin of the document; converting said sequence into a call format for the determined country of origin of the document by appending to the sequence a country prefix for the determined country of origin; and returning the converted sequence.