Is converting salary from Saudi Riyals to Sudanese Pounds – with the difference in exchange rate – considered usury?

It is permissible to convert paper currency of one country into paper currency of another country, even if the two عوضان (exchanged items) differ in amount due to their different types, provided that the exchange takes place hand-to-hand (قبض) in the same session. The receipt of a check or a remittance slip is considered equivalent to hand-to-hand receipt in the session.