Much debate exists whether explicit signalling is eventually required to create a reliable and integrated multi-service Internet. If yes, further disagreement exists, how such signalling has to be carried out. In this paper, we adopt the point of view that signalling of Quality of Service (QoS) requests must not be abandoned, given the high level of uncertainty about the future traffic mix in an integrated communication network. We present a flexible architecture, based on an extended version of RSVP, for signalling QoS requests. We approach the question of RSVP’s suitability for this purpose from two directions. First, we present the design of a QoS signalling architecture describing flexible, yet efficient interfaces between participating entities. Second, we report practical experience from our ongoing effort to implement key components of this architecture.