Ok I must be the only one who has a mixed view…
I personally work ad hoc hours (as can be seen from the times I post!) and am on call 24hrs a day with my current job, I would not be fussed if I had a work related call out of office hours. (But I am paid for this!)
Also my mates have no qualms about calling me whatever the time, I regularly get calls at 5 in the morning by drunken mates, to which I am happy to speak with ( I usually forget what they have said by morning!) However there is a difference between friends, and also mobiles to landlines. I would ring my mates at shit times but I would not call my mom at the same times (not that it would do me any good as she takes her hearing aid out!)
Whilst in Durham I also had my (Music Management) lecturers mobile telephone number, and once after a absinth fuelled night we thought it would be funny to call one up and sing South Parks “Shut your f***ing face uncle f*****�, very funny

at the time, wish I had have been a little more sober when I was putting my caller id to ‘not sent’, but hey I was wasted!
I did however remember when he asked to see me after a lesson, when it all came flooding back to me!

Out of order maybe, but he did offer me an E the first time we went out for a class trip so he didn’t take it much further!
And on the other hand I was President of the Students Union in Durham, and had to call out the Director of Higher Education at about 04:00 however he did thank me when he arrived as one of the students was suicidal and may have brought the establishment into bad light had they jumped off the roof, I don’t think he would have come out for any other reason! Either that or because they would have landed outside his office, and the smell would have been bad!
You say that the son answered the phone…. Did you get to speak to the guy? And is he going to be pissed with his son for been rude and not letting him decide if he was going to take the call? Or is everyone else here right that the problem could have waited?
If someone called for my mom I would
1) Ask what they wanted and if it was urgent
2) Wake her up and let her decide one if she wanted to talk to them
3) Let her be shitty with the person and give them a mouth full (assuming that the call was irrelevant, and not time sensitive)
I would feel a right idiot if I had said its late and hung up to find that her business had just been shut down my the Inland Revenue, or that one of her employees had been killed and she hadn’t turned out.