Plantronics (Clarity) WS-2620 Cisco 7900 Series IP Phone Push-to-Talk Handset. Push-to-Talk (PTT) handsets address the need for security in environments where background conversations must not be over heard on the telephone. Using Cisco IP network and this PTT handset any conversation can be conducted without the worries of eavesdropping. PTT solutions are also recommended for environments with loud intermittent background noise