Hello and welcome to the forum!
Telling an individual with PTSD to 'get over it' in regards to traumatic memories and anxieties related to it is unhelpful.
Is there a reason why he has shown reluctance to call? Sometimes PTSD sufferers go through long periods of extreme stress where direct communication or confrontation by an individual - no matter how good intentioned they are - can send them spiralling into stress due to the already overwhelming anxiety they find themselves in regards to their trigger.
Have you thought about reasoning a compromise? For my sufferer and I, texting is normally enough, and it is less stressful than if confronted by a voice face to face. Otherwise, perhaps there's a reason he may not like phone calls? Perhaps it may be one of his triggers associated with the trauma? (ei: if said family got into a car accident, maybe one of the parties was on the phone?) While it may be difficult, the best thing you can do is be open to compromise and understanding. He may not want to call because it stresses him - ask him if this is so. Ask him what you could do to alleviate stress, and how you could support him. Presenting ultimatums doesn't seem to be the best case here, unless he is refusing communication with you altogether. Telling a person with PTSD to 'get over it' is maybe the worst 'advice' you could ever give. Don't do it.
Is your sufferer seeing a therapist?
