Open Radar

 
Summary:

In my recent trip to Denmark (I live in the UK), I turned my phone on in the plane after we landed, and immediately received 6 emails, even tho Data Roaming is off (it's always off, I never, EVER use data when roaming, too expensive).

If I try to do any other data after turning airplane mode off, it fails (as it should). Just appears to be the initial "new country, new network...." type thing.

Steps to Reproduce:

Turn on airplane mode.
Get in a plane and fly to another country.
Turn off airplane mode
See the emails which have come in despite data roaming being off. 
Wonder how the hell this happened. Wonder if it'll happen again. Wonder how big the bill is going to be.

Expected Results:

No email. No data traffic. No crazy telco charges!

Actual Results:

Email! Data Traffic! Around £20 of data charges over 5 trips (between 3-10£/meg over 4 trips)

Regression:

Absolutely. This never happened with 3.x on my 3G. But on the 4/iOS4, happens on every trip.

Notes:

This is not a one-off case. Happened this week in Denmark (£3/meg), to my wife in Morocco (£6/meg) and Canada (£10/meg), and both of us in Amsterdam (£3/meg). I thought it was a billing error from O2, but it appears not. The amounts have never been much, so I just let it go, unti I actually got email, which was unexpected.

There was no WIFI anywhere around, and both phones are setup to not even ask if we want to connect to wifi, let alone do it automatically.

If I had to guess, it's doing this:

airplane mode turns off. cell radio turns on, finds a new, unknown network, but no network name yet / roaming status, so assumes it's ok to use it.

mail sees network and opens a TCP connection 

the OS sees that it's roaming and stops all NEW TCP connections, but the existing one stays open

mail downloads messages, and closes TCP connection

mail later fails to open a new one (which is good)