Engineers use information theory to analyze how noise influences information transfer, for example, in telephone systems. Cheong et al. (see the Perspective by Thomas) have now applied such analysis in biological experiments by monitoring the response of thousands of single mouse fibroblasts to stimulation with various doses of tumor necrosis factor (TNF). Signal transmission was surprisingly noisy, meaning that the cells could only really differentiate whether TNF was present or not. Such limitations of a single signaling pathway appear to be overcome by the cooperation of multiple signaling pathways in networks or by groups of cells collectively averaging their response to the same signal.