Does android switch to a different APN when in hotspot mode? I've tried turning on the portable hot-spot mode on my nexus-one and got a message from my operator saying that my plan doesn't cover data traffic made through the web.operator.com APN, as opposed to mobile.operator.com (my "usual" APN). That made me curious. Does that mean that android switches APNs when the hot-spot feature is active? And if so, is this a built-in feature/configuration option or an operator customization?

Update No, the phone doesn't switch to a different APN, but I'm still not sure what triggered the message from my operator...

Update There's kind of a persistent rumor that European Nexus-One phones get tweaked OSes, see the xda-developers forum threads [1] and [2], or google nexus-one forums [1] and [2]. One of the most likely tweaks seems to be the tagging of hotspot traffic, in order to be able to charge for it differently.
Also see http://forum.xda-developers.com/showthread.php?t=734138 for a discussion about how they might. Mechanisms other than APN change might include


Time to live
Request header
Data volume


Answer seems to be probably not.