Patent ID: 7027433

Claim:
A method of routing a call from a circuit switched telecommunications network to a packet switched telecommunications network, wherein the circuit switched telecommunications network is provided with an access to a user register, comprising the steps of: sending from a first network element of the circuit switched telecommunications network a first routing information query to an second network element, said query including a destination identifier of a called party, sending a response message to the first network element, said response message comprising routing information to the packet switched telecommunications network, sending from the first network element, according the routing information, a set-up message to the packet switched telecommunications network, said set-up message comprising the destination identifier of the called party, and when the call has been returned from the packet switched telecommunications network back to the circuit switched telecommunications network: sending from the first network element a second routing information query to the second network element, sending in response to the second routing information query a query message to the user register.