I'd say an hour or two hours. Any less and you kick people who are legitimately afk. Any longer and you're defeating the purpose of including it.
FFXI not only let you disable it, but also let you set the timer, because when it came out PS2s were still on dial up modems, and so were some PCs. So having a 10 minute no input disconnect made sense because if you were still online, you couldn't get any phone calls...
Maybe allow users to select between 30 minutes to 2 hours for XIV?
I don't know about anyone else, but when i had dial up, we had an incoming call display pop up to let us know when a call was coming in.... till we just got a second phone line, instead of using just the one.
-edit- was pretty funny that day.
me"mom, dad. we need a second phone line."
me "cause grandma and grandpa call too often, for too long for me to be able to enjoy the games you bought for me for my birthday."
parents"well that's not our fault, and we can't exactly tell them to stop calling."
me "no, but i could give up my allowance and try to convince you to get a second, long distance capable phone line."
parents *pick up phone to call phone company*
me *mission complete.* Que fanfare. Edited, Sep 5th 2013 12:25pm by YggdrasilSlepnir