Except where a call is made to a `specialised service' (see Section 2 Parts 11, 12, 13, 14, 15, 16 & 17), a call made to an exchange within the same charge group or to an exchange in an adjacent charge group is always a local call. All other inland geographic calls are charged at National rate. Information concerning call charges between two charge groups is contained in the Phone Book. for additional charge group information Customers can ring Operator Services on 100. Special arrangements apply for certain offshore islands - see Section 2 Part 9