Do you have a picture of the two of you having fun? Send him that... It is not to depress him more or anything its to bring back happy memories. Send him a pair of warm socks... He can't have too many of those and since you are not there to 'keep him warm' those will have to do. Send him clips of his favorite comic strip... Keep phone conversations light if you get to have any of those. Good Luck. Laughter is always the best medicine.