We present an actively multiplexed photon-counting detection system at telecom wavelengths that overcomes the difficulties of photon-counting at high rates. We find that for gated.detectors, the heretofore unconsidered deadtime associated with the detector gate is a critical parameter, that limits the overall scalability of the scheme to just a few detectors. We propose and implement a new scheme that overcomes this problem and restores full scalability that allows an order of magnitude improvement with systems with as few as 4 detectors. When using just two multiplexed detectors, our experimental results show a 5X improvement over a single detector and a greater than 2X improvement over multiplexed schemes that do not consider gate deadtime. (C) 2009 American Institute of Physics. [doi:10.1063/1.3247907]