Unless it's really important, I dont usually answer the call waiting.

We have the call waiting caller id, (someone calls, we get the beep, and the caller id shows the name) Usually, if my sister calls and it's important, she'll call once...then call back again a couple of minutes later. If she calls a third time, it's really important and then I'll say sorry to whoever I'm talking to and I'll answer my sister's call.

My phone etiquitte (sp?) pet peeve. People who interrupt me while I'm trying to talk. (actually, that annoys the hell out of me when I'm talking to someone in person too)

I got that pet peeve when I used to work inbound telemarketing (people called me, I didnt call them) I'd get people calling for the crap that's "As Seen On TV" infomercials...all that junk, and I'd get credit card applications.

I'd be trying to answer the person's questions, but instead of letting me read the stupid script and answer their questions, they'd keep interrupting me with new questions or repeating the old question a zillion times and not letting me finish answering them. Happened more often than you'd think. Annoyed the heck out of me.