A modular housing for outside plant telecommunication equipment includes a main enclosure for containing common electronic equipment and an auxiliary enclosure for containing input/output (I/O) circuitry to said common electronic equipment. In this way, different configurations of I/O circuitry can be accommodated only by changing the auxiliary enclosure. The design and fabrication times for making housings is reduced by the smaller size of each enclosure. Upgrades can often be accommodated by only changing one of the main or auxiliary housings.