The TD-3H/B is a multi-channel selective call intercom which supports a maximum of 4 stations. On loop-wiring, five TD-H station models, intermixable, can be configured to all-master, master-selective system or mixed. aditionally, using a potential station(s), PanTilt MY and/or audio IE/IF door stations (2 max) and paging zone(s) may be incorporated.