"Don't assume because it makes an ASS out of U and ME". Right, should've taken that to heart when I switched from a Nokia cell phone to my new SPV C500. What happened?
Well, on my Nokia it worked this way: calls on line one had call waiting notifications turned on. So when I was in a call, I was notified that a call was waiting to be picked up when someone else called. However, for line two, I hadn't activated it. So when I was in a call, the caller was routed to the voice mailbox immediately. When I wasn't in a call, the phone rang when someone called on line two.
Not so on the SPV C500: here, callers on line two are always (!) routed to the voice mailbox, no questions asked - unless you turn on "Provide call waiting notifications" on line two. Whoops. That was quite a nasty surprise because line two is the incoming line for business calls.
Speaking of snags: my Nokia provided indication of whether a call came in on line one or line two - the SPV C500 doesn't seem to have this functionality, or I haven't yet found how to activate it. If you, dear reader, happen to know, let me know.