This question is a follow up to a previous question asked by @AvengingEarth
I'm interested in taking a step further.
All conditions are as in the previous question except that there are two people and each has their own smartphone. They have no network and no other equipment or computer to help them. Assume only the two phones. The owners have superuser skills but no way of changing anything except possibly software. However there is no network to download from, no extra computing power, and they would have to develop any software purely on the standard factory-provided software and firmware plus maybe a few games and things like Microsoft Office for mobiles.
My full question follows:
Would two smart phones be usable as an intercom on a human-life-supporting alien planet? If so, what range would be possible assuming there is no other radio communication going on anywhere on the planet.