1. Pertaining to an arrangement or sequencing of networks, circuits, or links, in which the output terminals of one network, circuit, or link are connected directly to the input terminals of another network, circuit, or link. Note: For example, concatenated microwave links constitute a tandem connection. 2. A switching system in the message network that establishes trunk-to-trunk connections. Tandems may be further identified as local tandems, LATA tandems, or access tandems.