The patented whoopFAST™ Small Cell Interface (SCI) delivers 4G/LTE in-building coverage for the four Tier 1 mobile network operators, serving >98% of users Day-1. It includes ten radio inputs and four outputs. The inputs include eight small cell (femtocell) inputs and two over-the-air (OTA) inputs. The OTA inputs use band-specific repeaters to boost the OTA signal for simulcasting throughout the in-building coverage area. The small cell inputs are operator-specific, with the capacity of each small cell switchable to any of the four outputs. Up to 50 antennas may be connected to each SCI. A Whoop Antenna Array Element (AAE) is connected to each antenna to boost output power through the antenna. This enables Enterprises to distribute a femtocell signal to a coverage area 50x larger than the area of a typical stand-alone femtocell. The SCI passive switch matrix optimizes the delivery of capacity where required in the coverage area. Capacity may be simulcasted throughout the building, or mapped to targeted coverage zones, based on enterprise capacity requirements and available signal source capacity.