Cisco 7900 Push To Talk Handset for Cisco IP 7900 Series Phones has a button on the handset for quick convince. Cisco Push-to-Talk (PTT) handset aids in the defense against unauthorized eavesdropping on background conversations by breaking up the conversation flow. Cisco 7900 Push-to-Talk (PTT) handset is equipped with a single pole, single throw switch, clear static-free reception, electret transmitter provides extra-clear transmission, and hearing aid compatibility.