title: iphone 3G data network timeout?
body: <p>My iPhone app sends data persistently over the network, and can handle having the network completely unavailable for a time. However I do my dev on an ipod and have difficulty testing 3G connectivity issues; My question: is there  period of non-connectivity, while an app is in the foreground, after which the iphone will stop checking for the network, such that there are no bars and reachability returns 0 until the user "wakes" the phone, e.g. by locking/unlocking? Or can e.g. 1 hr without data network pass and the iphone will recognize that the network is back and reachability will start returning true (I am polling every 1 minute while there is not connection to my server). </p>
  
  <p>This is my experience with wifi: if, while running my app, the ipod hasn't connected to a wifi network for 1/2 hr, it stops looking for networks, and I need to lock and unlock it to stir the device into looking again. </p>
  
  <p>One other thing: the iPhone has the screen dimmed by the proximity sensor while all this persistent network use is happening.</p>