DIRECTORY NUMBER PORTABILITY IN TELEPHONE NETWORKS

摘要

Portability of directory numbers in telephone networks, particularly so - called intelligent networks, may be provided without modification of the cal l processing software at originating network node switches, by associating each call to a ported number with an Initial Address Message comprising a Location Routing Number for the recipient switch as the Called Number and the ported directory number as the Original Called Number. At a boundary with a network which uses a Location Routing Number, a Generic Address Parameter and a Forward Call Indicator flag for identifying calls to ported numbers, a network element creates a modified routing message by converting the Original Called Number to a Generic Address Parameter and setting a Forwarde d Call Indicator flag to indicate a translated originally-dialled called number. Th e network element then uses the converted Initial Address Message to route the call in to the second network. Public Office Dialling Plan or Termination Attempt triggers may be used to interrupt processing of a call to the ported number and initiate a query to a Service Control Point database far the corresponding Location Routing Number for inclusion i n the Initial Address Message. Alternatively, call forwarding at the donor switch may be used to provide the Location routing Number for the originating switch to include in the Initial Address Message.