There is provided mechanisms for establishing a communication session with a local serving network. A method is performed by a terminal device. The method comprises obtaining an indication of traffic to be communicated. The traffic is associated with a traffic descriptor. The method comprises selecting a URSP rule for the traffic to be communicated in a communication session with the local serving network. The URSP rule is selected in accordance with the traffic descriptor and in accordance with a validity condition for the communication session. The validity condition at least pertains to network support for IMS in the local serving network. The method comprises establishing a communication session with the local serving network for communicating the traffic according to the selected URSP rule.