Kaiser it's the advice nurse, which honestly is never helpful for me so I usually just email my doc. At this point though they told me to call L&D directly with questions.
From my experience, it's fairly normal for it to be handled by the receptionist. I've had 3 OBs recently. One had an advice nurse, but the other two just have the receptionist relay messages to the doctor. If it was serious (unfortunately I had a couple of those situations), then the receptionist would put me on hold and track down / interrupt the doc. Otherwise I'd just get a call back.
My OB didn't have an advice nurse, but had a nurse and the receptionist would usually put me through to her or her vm. She'd run my question past the dr. and either the nurse or dr. would get back to me.
I am now Kaiser, but wasn't when DD was born, and had to relay info through the receptionist. I hated having to share personal info, especially b/c she was a beeotch.
Re: When you call your doctor for advice...