iPhone routing question

[Druce MacFarlane]

So, has anybody tried this? If your iPhone is connected to a WiFi network and there is no route to the outside world, does the iPhone automatically fall back to the 3G network the way a PC might if it had multiple routes?

I ask this because I would like to create a setup for AirPlay using an Airport Express that wouldn't have Internet access. I would like to connect to the Airport for AirPlay, but don't want to sacrifice Internet access to do so.

If this isn't a "supported" configuration, is has anybody gone in at the root level in order to play with the routing tables to make this work?

Any experiences you hackers can share with making this work would be appreciated.

 

[BigB]

I haven't tried on iOS4 or on the iPhone4, but on my 3G running 3.1.3 when my wifi internet went down, I couldn't get online with my phone at all unless I turned off the wifi..