Reswitching of connection networks

In certain types of connection networks, it is always possible to unblock a blocked call by moving calls already set up in the network. The following results relating to these networks are derived in this article. 1. Bounds on the number of calls which must be disturbed to unblock a blocked call. 2. Bounds on the relation between the number of calls which are already set up in the network, and the number of calls that must be disturbed to unblock a blocked call. 3. Methods of systematically changing connections to unblock a blocked call.