Abstract: The present invention relates to a method for connection establishment in a system comprising multiple radio access networks for accessing core network services. A terminal is registered via a first radio access network to an element providing access to circuit-switched core network services. Establishment of a connection via the first radio access network to the element is requested for accessing circuit-switched core network services. As a response to detecting a failure in the establishment of the connection via the first radio access network, attachment to the element via the first radio access network is released and a connection establishment procedure for accessing circuit-switched core network services via a second radio access network is initiated.