I've done 10 legs so far this year on AA, all with miles credited to AS. You definitely have to call but I've never had a problem getting it input (or credited) on the first try. AS' partners used to be much worse about sending credit over, but I haven't had a problem for several years.

I've been flying AA so much this year that I actually considered switching to AAdvantage for credit. Until I saw that gold members only get 25% mileage bonus compared to AS' 50% for MVP's. It sure would be nice to have that MVP status mean something at AA, though.