ISDN QSIG Path Replacement Page 1115 of 1814International ISDN PRI Feature description and administrationISDN PINX DNThe Path Replacement feature must scan the PINX nodes to find the optimumpath to a remote PINX node. To accomplish this trunk optimization function,Path Replacement makes non-call associated requests (D-Channel messagesonly, no B-Channels are used) to the Path Replacement feature at the remotePINX node. The requests are not directed to any existing DN on the remotePINX node, but to a processing function on that PINX node.To be able to route those types of calls through the network from oneoriginating node to a destination node, an ISDN PINX DN must be definedfor each PINX node in the network.The ISDN PINX DN is a DN taken from the customer’s numbering plan usedto aid with the routing of network calls. It does not correspond to a realterminal on the node, so it is never busy. The ISDN PINX DN uses the samenumber of digits as the numbering plan; either UDP or CDP. It is defined sothat the Path Replacement feature on a distant node can make non-callassociated calls to the Path Replacement feature on another node when noparticular destination exists. Those calls are made using existing routingconfigurations, e.g. a CDP distant steering code or a UDP location codeexpecting a fixed number of digits. For example, the far end PINX node hasa digit sequence composed of the steering code plus the ISDN PINX DN withthe same length and digit sequence used to route normal calls from the distantnode to the local node for CDP type calls and location code plus a 4 digitISDN PINX DN for UDP type calls.One ISDN PINX DN should be configured per network location. This ISDNPINX DN is used for the Path Replacement feature and other features such asElectronic Lock Network Wide/Electronic Lock for Private Lines and CallPickup Network Wide features.No user or feature other than Path Replacement, Electronic Lock NetworkWide/Electronic Lock for Private Lines and Call Pickup Network Widefeatures will be allowed to dial the ISDN PINX DN. If a user dials this DN,they will receive overflow tone.
