A method and an apparatus to determine the supported quality of service in an anticipated network session between a calling device and a called device that exchange information between at least two independent IP networks. The calling SIP device generates and sends an SIP message to a first IP network, which message is then propagated to a second IP network, and so on. The SIP message includes a desired quality parameter, i.e., maximum delay requested, and an accumulated delay parameter inserted in the body thereof. The accumulated delay parameter is modified by cumulatively adding delays between respective devices and/or networks between the calling and called devices. At the receiving end, the called device compares the requested and accumulated/supported delay, and then reports the results of the comparison back to the calling device via a return acknowledgement packet so that the calling device may decide whether to proceed with or reject the call. The calling and called devices may comprise SIP telephones, data terminals, or multimedia devices.