WMT1A - 

Input/Line Transformer, 2-3/8 in. Height, 2 in. Width, ± 2 dB Frequency Response

WMT1A is a general purpose matching transformer that allows proper connections between high (10 kΩ) and low (600 Ω) inputs and outputs. It can be used to balance an unbalanced line or provide isolation between two pieces of equipment.
Designed especially for matching inputs from, or outputs to, a 600-Ohms line. Used to connect telephone systems to most public address amplifiers for telephone paging.