Iridium 9575 Extreme PTTIridium 9575 Extreme PTT makes the power of fast, simple, secure and adaptable group communication available on the toughest, push to talk enabled satellite phone on the market all at the push of a button. Powered by the worlds furthest reaching network, the Iridium Extreme PTT is engineered to support high intensity users with the worlds first global push to talk service as well Iridiums standard global voice calling, SMS and SOS. When using PTT ,