Complex sentence: The way to split the numbers is defined in the National Numbering Plan 2003 as XXXX-NNNNNN where "XXXX" indicates the network operator and telecom circle, and "NNNNNN" is the subscriber numbers.
Split into simpler sentences: The way to split the numbers is defined in the National Numbering Plan 2003, as XXXX-NNNNNN. Where "XXXX" indicates the network operator and the telecom circle, there "NNNNNN" is the subscriber numbers.