The WBS/WTR system, since it does not have a call feature, poses a challenge for interfacing with our TW-47 2-way radio interface. The use of the SA relay is the way to go, However, since the SA circuit disengages the talk path from the party line, when talking to the radios, one would not be heard by the other WTR beltpacks in the system.What you could try it is routing the SA talk path both to the radio and also back into the WBS basestation, so the other packs will hear the pack initiating the call to the radios, when not heard on the PL path. You can use an RDL Stick-On DA (http://www.rdlnet.com/product.php?page=38) or something like it to distribute the SA output back into the AUX input of the WBS while also sending it to the TW-47 and on to the radios.