It's program dependent. It seems that in most programs, the intern, while in psychiatry, is on call at least q-week. While in medicine, most programs seem to have them "belong" to medicine. "Lite" internships, caseloads, and call schedules are not only insulting to psychiatry residents, but does them a disservice to their training.
In that sense, I believe that most programs have the psych intern doing medicine call while on medicine. This is commonly q4, often having to work every saturday morning as well, for example. Worse if you're in the ICU or CCU or tele.
There's no way you're taking medicine call from home unless you're in the twilight zone somewhere...