You can not call 911 directly on the Inmarsat phone. The unit does have an 'Emergency SOS' button that is pre-programmable. You can set it up to call someone, send an alert via text or email message and the prime usage is to register yourself with GEOS, a global rescue service and they will get the message and immediately alert authorities. The 911 Service is provided by a private company who will then alert authorities in your area. This is the US and Canada only.
This servie applies to Iridium handsets 9505, 9505A, 9575, 9575N, 9555 & 9555N as well.