Does Wi-Fi turn off when locked

I can say conclusively, the iPhone stays on Wifi when sleeping. How do I know this?... I am running my own mail and chat server, and I see it in the server imap logs as well as chat sessions that are maintained on Wifi addresses long after the phone has gone to sleep (like overnight). When the phone leaves my house, the log flips over to an AT&T address. But as long as the phone is in my house, the IP attached to the server is the Wifi IP address of the phone (actually three of them, in my case).

Probably because as the person pointed out above, the phone just goes dormant. As we all know, the second we turn on the iPhone, it changes from 3G to WiFi within a second or two. It maintains it's IP address while sleeping so that it can connect almost instantly within a second or two once the phone is used though during sleep, it is using 3G.

In 4.0 and 4.0.1 the wifi was persistent on the iphone.

In 4.0.2 they changed it to disconnect after being in sleep for 10 seconds.

However, if your data connection is turned off in the settings the wifi will remain on when in sleep.

This was confirmed by a member of Applecare.

I refuse to believe it was ever added on 4.0.1 and 4.0 because I have three new phones here, an iPhone 4, an 8GB 3GS and a two month old 32GB 3GS all running 4.0. Persistant WiFi has not been existent on any of them and was never shown as a feature on their website.

Apple Care has been known to be wrong a time or two.

The easiest way to find out if it disconnects or not would be to log into your router when your phone is in sleep mode for more than 5 min. Check on your router for current connections. If your phone isn't listed, then obviously it shuts the WiFi off.

When IPHONE is sleeping and wakes up WiFi icon is there (of course if wi-fi is turned on and available. If you turn the PHONE OFF using the top button then it is not connected.

My iphone 4 doesn't display the WiFi icon at all, even after restart. Even though it says I'm connected in Settings.
It does not appear to be working, either, as apps that require wifi aren't working.

Yes it does. When I press home button while phone is locked to show up the lock screen, I see Edge icon and within a second, it changes to Wifi. Which means wifi was off but turned on at the lockscreen even when phone was locked. So I guess the correct answer is it turns on and off with the display of the phone.

Actually I think all that means is, is an indication of which cell network you are on. The wifi is always on, but occupies the spot on the screen. Call it a courtesy glance at the cell connection. It does not mean the wifi was off. The wifi is always on, even when sleeping. Has to be, to pick up e-mail either push or a fetch interval. All that stuff continues to run during sleep.

Persistent wifi was a documented feature with the release of 4.0 in the full release notes.

This was removed in 4.0.2

Wifi DOES turn off when the screen is off after 10 seconds. But it connects so fast you often dont notice its off. You can tell by viewing your routers status page if it offers this.

You dont need wifi to get push notifications, it does this via the celluar network when the wifi is not available.

I do not use push notification. Just IMAP fetch. It uses wifi all night long. I know this because my mail server (IMAP) is on my own network, and I can see the IP in the log files.

I have the iphone 4. I am having a hard time with my WiFi connection. It shows that I am connected on the settings screen but on my home/main screen the WiFi icon does not show. If I go to networks, then it will pop up in the upper left corner. It disappears after a few minutes. Anyone know how to fix this? Could it be due to low WiFi signal? I'm at home trying to do it

Thanks for your post!!! It helped me with my problem. As soon as I turned off my data connection,my WiFi icon popped up in the corner. Is it ok to leave the data connection off?

This is a copy/paste from a post on here. It fixed my problem which was the exact same as yours!!!
In 4.0.2 they changed it to disconnect after being in sleep for 10 seconds.

However, if your data connection is turned off in the settings the wifi will remain on when in sleep.

This was confirmed by a member of Applecare.

Thanks... I found that out on my own too... but what are the implications of having Data Connection turned off in settings? I found several apps complained and asked me to turn it back on.