Systems, methods, and computer program products for providing a manual ring-down communication line using session initiation protocol

摘要

Systems, methods, and computer program products are provided for manual ring-down communication using Session Initiation Protocol (SIP). A first SIP user agent transmits a message to a second SIP user agent over an Internet Protocol (IP) network to establish a SIP session. The first SIP user agent determines that a signal key associated with a first communication device has been selected and transmits, to the second SIP user agent over the IP network, a start event message to cause a second communication device to activate an alert. The first SIP user agent determines that the signal key has been released and transmits over the IP network an end event message to deactivate the alert. The first SIP user agent transmits, to the second SIP user agent over the IP network, one or more subsequent INVITE messages at a predetermined repetition rate to refresh the SIP session.