A method for operating an IP Multimedia Subsystem Application Server to facilitate a communication session between a first user and a second user at a required Quality of Service (QoS) is provided. The method calls for receiving a notification that a Policy and Charging Rules function (PCRF) associated with the first user has not authorized the required QoS. The notification includes an indication of additional QoS required by the first user in order to achieve the required QoS. Authorization for the additional QoS for the first user is then requested from a PCRF associated with the second user. The method then calls for receiving a notification that the PCRF associated with the second user has authorized the additional QoS, and notifying the PCRF associated with the first user that the additional QoS has been authorized for the first user.