the delivery of emergency services to users of a set of communication devices in a packet - switched network is enabled by a method that determines a routing key corresponding to a particular directory number that is associated with a particular communication device , and stores the directory number and the corresponding routing key in a database accessible to a packet switch . the steps of determining and storing are executed during a provisioning phase , in the absence of an emergency call placed by the communication device . the routing key is indicative of routing instructions to be followed by the packet switch upon receipt of a future emergency call placed by the communication device . when the call is received by the packet switch , it will consult the database to obtain the routing key associated with the directory number and send the call as well as the routing key over a path dedicated to emergency calls .