I have a Samsung Galaxy Ace, with quad-band I believe. It is possible to see the current connection network type, e.g. UMTS, EDGE, etc, by going to Settings -> About Phone -> Status. But it does not tell which frequency band it is on. Is it possible to find out which frequency band (either exactly, or just which of the four major bands) that I am using?
Based on avirk's hint, I found a way. First press the code *#0011#
It is obvious that it's using 900MHz band, from the "GSM900".
UMTS WCDMA example:
UMTS can use two different physical layers (low level radio) UMTS-FDD and UMTS-TDD. Android just shows WCDMA, which I think is the same as UMTS-FDD, but perhaps it can refer to both of them. By looking up the channel number here you can tell the frequency bands and whether it is UMTS-FDD or UMTS-TDD.
In the above example it is using UMTS-FDD, the down-link channel (Rx) is in the 2100MHz band and the up-link channel (Tx) is in the 1900MHz band.
You can try dialing
and then going to "Phone Information".
That will show details about the network like cell tower ID and network type. As you can see from the below screenshot, it shows "EDGE" mode :-
Also, this may only work on stock Android builds.