An RS-703 belt pack is designed to work through a TWC-701 multiplexer interface. If you plug the RS-703 directly into a single channel of PL, it will be confused and show a constant call. The TWC-701/704 product takes two channels and combines them down a single microphone cable (3-pin XLR) by putting the second channel on the "power Pin" (pin 2). 
This gives a constant DC power "tickle" to channel two (B) and the belt pack sees that as a call signal.The solution would be to put one or both the channels going to the BP through the TWC-701/704. Then, through the V-Pak software, you could flip the call on channel "B" to a hypersonic call, instead of the DC call that is native to the Clear-Com PL line.