The present invention provides a method of establishing a call to or from a user equipment in a wireless communication system comprising a first wireless network and a second wireless network, the second wireless network having an association with the first wireless network, the wireless communication system having a serving node and an application server capable of communication with said serving node, and the method comprising: receiving a message from said serving node at the application server, said message having information regarding network capabilities of said user equipment; and determining at the application server whether to anchor said call in the first wireless network or the second wireless network dependent on said information regarding network capabilities of said user equipment.