Mostly right. SCIF phones are always press to talk with speakerphone disabled. Typically they are very simple POTS phones, with high roll-off lowpass filters wh

Mostly right. SCIF phones are always press to talk with speakerphone disabled. Typically they are very simple POTS phones, with high roll-off lowpass filters where they exit. Having a smart PABX which can transparently route cell calls to internal numbers is very important to making SCIFs functional. It was interesting to read that Hillary Clinton had problems at State because her staff couldn't access their phones in the office - primarily SMS or BBM I think.