Described are a method and system for determining whether to establish a call over an internet protocol (IP)-based network. A network device inspects an IP packet to determine that the IP packet conveys a message to initiate a call. The network device determines a shortest path through a link-state network to be taken by traffic associated with the call if the call is admitted. The network device also determines whether each link in the shortest path through the link-state network is available for supporting the traffic associated with the call and issues a message that rejects admission of the call if at least one link in the shortest path through the link-state network is unavailable for supporting the traffic associated with the call.