Abstract: In a telephone network having a plurality of network nodes, each having a unique network address and using out-of-band signalling for call setup and routing, a method is provided for the routing of calls to a "ported" directory number which has been ported from a donor network node to a recipient network node. The method comprises the steps of (i) routing the call, using the ported directory number as the Called Party Number, from an originating network node towards the donor network node; (ii) intercepting the call at an intermediate network node between the originating network node and the donor network node, through which intermediate network node calls to the donor network node must pass; (iii) converting the ported directory number to a network address of the recipient network node; (iv) routing the call to the recipient network node using said network address; and (v) at the recipient network node, completing the call to the ported directory number.

Abstract: Portability of directory numbers in telephone networks, particularly so-called intelligent networks, may be provided without modification of the call 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 Forwarded Call Indicator flag to indicate a translated originally-dialled called number. The network element then uses the converted Initial Address Message to route the call into the second network.