A method, session managing node and arrangement for providing a network service address of at least one network service of a first operator IMS network to a third party service provider (3PSP) are disclosed, wherein the 3PSP has no business agreement with the first operator. A first application of a mobile station communicates with a second application via a first network, resulting in the setup of an IMS session between the mobile station and the 3PSP. A network service address of at least one network service, provided by the first operator IMS network, is inserted into a SIP message of the IMS session in a session managing node of the first operator IMS network and delivered to the 3PSP, 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.