A method, a session managing node and an arrangement for providing a network-service address of at least one network-service of an IMS network (401) of a first operator to a third party service provider (403), wherein the third party service provider has no business agreement with the first operator. A first application (404) of a mobile station is communicating with a second application (405) via a first network (406), resulting in the set-up of an IMS-session, between the mobile station and the third party service provider. A network-service address of at least one network-service, provided by the IMS network of the first operator, is inserted into a SIP message of the IMS-session in a session managing node (600) of the IMS network of the first operator and delivered to the third party service provider, where it is forwarded to the second application. If required, the second application may access the one or more network-services via the first network, using the retrieved network-address.