There are a number of themes going on here, and it's sort of up to you to decide which you think is the main theme:
- For Eddie and Doc, the main theme is how the war (and just the passing of time) has separated them from their family and made their families seem in some way like strangers. Both of them have parents who can't really understand the technology that is allowing the call to happen. Eddie has a little brother who has grown into a man (voice-wise) but has no real clue about what is going on in Eddie's life (Pete doesn't understand about the war).
- For Paul, the main theme is imagination and its importance. His call is successful even though he doesn't talk to his family. That's because he gets to spend the whole time picturing his home and what's around it.
- So perhaps you can say the whole thing is about how we relate to the past and to things that are in our lives but not with us. We grow apart from our past (like Eddie and Doc have) in real life, but in our imaginations, it's still the same and we may be happier when we just imagine the past instead of actually trying to go back and relive it.
scaniapriest is a big dick
In the story "Calling Home" the men are stationed in Chu Lai. New technology allows for Paul and his friends to make a call home via the MARS phone system. Everyone is excited about the new technology. Paul is advised when he talks with his parents to sound positive and make it seem like he is on a vacation instead of at war.
Eddie calls home first and talks with his family. He shares his conversation with Paul by telling him what everyone had said.
Paul's turn arrives. While waiting for the call to go through he begins to recall events and details about his life at home. He can see each item in his home and their location. The phone starts ringing. He pictures his dad putzing around the house as he fixes items. He sees his mother vacuuming. He mentally looks at the telephone that is black because his father does not like pastel telephones. His memories have taken him home.
No one answers, but he has been home anyway, even if has been only in his mind.
The themes that I have identified in the story are the theme of man versus machine. The story opens with a big discussion of the excitement over the new MARS system which now can help a soldier to be able to call home. However, despite technology, Paul can only go home through his memories.
The other theme is that of real versus not real. Paul has created a reality for himself by picturing the details in his mind. Even though he never talks with his family on the phone, he has mentally communicated with them.