Please avoid using headsets with a 3.5mm jack, such as iPhone headphones or even expensive Bose headphones that are fancy headphones designed for great sound output that happen to have a mic. These devices have a tough time registering as the default input/output on your computer, and often have insufficient noise-canceling capabilities when plugged into a computer. As a result these can present bad call quality to your customers.
These are the headsets we do recommend for use with Kixie:
For the Kixie PowerCall Dialer / Computer Dialer: