I can't recommend specific IC's but a couple DTMF decoder chips and some basic logic would work.
Normally your RF receiver would always be receiving and feeding it's output into the DTMF decoders, when the first one received the tone it was waiting for it would turn on the loud speaker. When the second DTMF decoder received it's signal it would turn off the loud speaker, reset the first DTMF decoder, and then reactivate itself. Kind of like two SPST tone activated switches in series.