Redirection of calls to ported directory numbers in telephone networks

A method of routing calls in a telephone network having a plurality of network nodes each having a unique network address and using out-of-band signalling messages for call setup and routing, said network nodes including a donor network node from which a directory number has been ported, a recipient network node which has received the ported directory number, a plurality of originating network nodes, and a predetermined intermediate network node through which all calls routed from said plurality of originating network nodes to the donor network node must pass, the predetermined intermediate node being set up for intercepting calls to ported directory numbers and initiating conversion of their associated signalling messages, the method comprising the steps of:

• at one of said originating network nodes, creating a signalling message for a call to the ported directory number, the signalling message including the ported directory number as a called party number parameter, and routing the call from said one of said originating network nodes towards the donor network node;
• intercepting the call at said predetermined intermediate network node;
• converting the ported directory number to a network address of the recipient network node and incorporating said network address in a further signalling message;
• routing the call from said predetermined intermediate node to the recipient network node using said further signalling message;
• and
• at the recipient network node, completing the call to the ported directory number.