摘要 |
An active call between two parties can be marked as a non-preemptable call if one of the two parties is an authorized agency that desires to prevent premature termination of the call by a third party. The authorized agency sends a signal to a main switch to indicate that non-preemptable call status is desired. The newly established call status is then propagated to other nodes in the system to prevent premature call termination. Non-preemptable status can also be granted to some calls based on the destination of the called number, such as in 911 calls. |