A resource reservation scheme is an important mechanism of providing guaranteed QoS to applications. Today the only protocol that is standardized by IETF is the resource reservation protocol RSVP. Development of the next generation of signaling protocols is still open for research and development. We now propose SOS - a simple signaling protocol for guaranteed service connections. It overcomes poor scalability of RSVP and is simpler than existing proposals: Our protocol does not require per-flow soft states in core routers; it is robust and can handle losses of all types of signaling messages. Simple operations in the routers allow processing of 700 thousand messages per second.