IP telephony presents a tremendous opportunity to service providers to offer both traditional services as well os a range of creative new services. However, there are substantial challenges to be faced in supporting a resource management framework that is adequate for telephony, and in providing a signaling architecture that enables these services while preserving user privacy and preventing theft of service. This article describes the distributed open signaling architecture, a framework for call signaling and resource management that meets these needs. A key contribution of our work is a recognition of the need for coordination between signaling, which controls access to telephony-specific services, and resource management, which controls access to network-layer resources. We evaluate one approach to resource management in the backbone, consistent with our architecture, using signaling for aggregates of flows. Using traces from cells on the AT&T long distance network, we show that the multiplexing gains achieved by such aggregation con achieve most of the benefits of per-flow signaling, while avoiding its overheads. We also evaluate scheduling algorithms in order to understand their effect on the end-to-end delay experienced by voice packets.