How can I see a wireless network's frequency and/or channel?

NetworkManager is showing a number of different wireless networks available in my neighbourhood. I would like to know what channels the other wireless networks are operating on. How can I view these wireless network's channel information?

I am aware of the iwlist scan command but it does not see most of the networks that NetworkManager sees: the networks shown by running sudo iwlist wlan0 scan are completely different from NetworkManager's list.

You can just use the nm-tool command, it shows the information from NetworkManager it self.

nm-tool will list all of the visible wifi networks' frequencies. The command sudo iwlist frequency will give you a list of their corresponding wifi channel numbers.