PURPOSE: To optimize a call variance ratio to each exchange as a satellite communication network by providing a share ratio management function calculating the number of available lines based on the number of lines of each of plural exchanges and the number of blocked lines and deciding at any time and managing the call variance ratio to each exchange from the available line number calculated of each exchange to a satellite exchange.

CONSTITUTION: A satellite exchange 5 is started periodically and receives the number of real line of each of plural exchanges 7, 8, 9, 10, 11 via a common signal line 6 at first, receives a current blocked line number via the common signal line similarly and calculates an available line number based on the receives real line number and the blocked line number. Then an index of management standard decided in advance corresponding to the available line number of the exchanges 7, 8, 9, 10, 11 is obtained and whether or not the index is identical to the preceding index is collated and when they are identical, the variance ratio is not revised and the communication is terminated, and when they are not identical to each other, the variance ratio of each of the exchanges 7, 8, 9, 10, 11 mated to a new index is decided and the new variance ratio is informed to the exchanges 7, 8, 9, 10, 11 via the common signal line 6.