Abstract: An arrangement that enables an adjunct processor to determine the service status of switching system communication ports to which the adjunct processor is connected, without reliance on switch-to-adjunct status-conveying messages. In-service and idle ones of the ports participate in calls on a rotating basis. Following receipt of N calls, where N is the number of in-service ports connected to the adjunct processor, the arrangement determines whether each port that is presently designated as being in-service and idle has participated in one communication before a port has participated in a second communication. The arrangement then treats as out-of-service any port presently designated as being in-service that has been so determined a predetermined number of sequential times. It also selectively designates as in-service ports that have participated in communications since the last determination had been made.

Abstract: To provide robustness within the SMSI data communication protocol, a voice message system stores all message-waiting update (MW) messages that it sends to a communication switching system, and periodically transmits a properly-formatted MW message bearing intentionally-corrupted data to the switching system over their connecting data link. After each transmission the voice message system awaits the return on the data link of an invalid message-waiting (IMW) message. If the IMW message is returned within a predetermined time period following transmission of the corrupted MW message, the voice message system treats the data link as viable and clears the stored MW messages. If the IMW message is not returned within the predetermined time period following transmission of each of two corrupted MW messages, the voice message system treats the data link as not viable and, following repair of the link, re-sends the stored MW messages to the switching system.

Abstract: The functionality of the SMSI protocol is extended by adding to the SMSI protocol messages having the same format as the conventional SMSI protocol messages but implementing leave word calling functions for a voice message system adjunct processor and integrating maintenance functions of an adjunct processor and an SMSI protocol-to-non-SMSI protocol converter.

Abstract: The functionality of the SMSI protocol is extended by adding to the SMSI protocol messages having the same format as the conventional SMSI protocol messages but implementing leave word calling functions for a voice message system adjunct processor and integrating maintenance functions of an adjunct processor and an SMSI protocol-to-non-SMSI protocol converter.