How To Put Apple Iphone Into Cellular Phone Field Test ModeAugust 10th, 2012 by Craig Mullins
Want to know how to put your Apple Iphone into field test mode to look at all the special goodies?
I needed to do it to get info on two parameters. What network frequency I was running on at my farm and how much signal power I was getting at a certain location to find the best place to stand and make phone calls and be able to get on the internet. Getting data access was a pain, so hoping this process gives me some insight. My AT&T cell phone service sucks pretty bad in Burson, CA near Lake Comanche area.
I called AT&T, but they were having no part in giving me any answers to the questions I had above.
The reason I want to get those 2 parameters is so I can put a mini cell tower on my property. So I need to know what frequency of equipment to buy and the best location for the actual antenna placement and where to aim it.
So time to snoop around a bit.
So if you go to your keypad like your trying to make a phone call enter this number:
Then hit the call button; you’ll get a screen that looks like this. Your now in cellular phone field test mode.
If you look in the top left corner that is your cell phone signal level. The signal strength is measured in Decibels (db) it’s usually a negative number. -51 is a full signal, -105 is no signal. A lower number is best. Mine is currently -86 db. I should mention that this isn’t actually at my property near Valley Springs, CA. I’m actually in Pleasanton, CA right now. So the numbers won’t be what you’ll get.
Next thing I am looking for is the frequency my phone runs on. So we’ll click on “UMTS Cell environment“, then click on “UMTS RR info“.
Now look at the menu item “Downlink Frequency” mines at 9721. If you are running on the 1900 MHz cellular band the Downlink Frequency code will be between 9662 and 9938. If you are on the 850 MHz spectrum the Downlink Frequency will be between 4357 and 4458 MHz. So in Pleasanton I’m on the 1900 band at my home.
The next item to check out is the “Uplink Frequency“. Mine is at 9321. It’s not shown on the picture above, but it’s on that same screen. Just scroll till u find it. If you are running on the 1900 MHz cellular band the Uplink Frequency code will be between 9262 and 9538. If you are on the 850 MHz spectrum the Uplink Frequency will be between 4132 and
So I’d want to buy a device that runs at the 1900 MHz range; at least at my home in Pleasanton.
The next thing I did was walk around the house on top of the roof . I moved to various spots on the roof and held my phone at various angles to find the best reception area for my antenna mount location. Be sure to wait 10 – 30 seconds between movements as the phone display doesn’t update the decibels instantly.
Something that may help is a site like Wireless Advisor. You can input your address and it will tell you all the cell phone carriers with towers in the area and what frequency they run off of.
In the case of valley springs they had multiple frequency’s listed for AT&T, so it wasn’t much help. Putting the phone in field test mode is the only answer for that city for an Apple Iphone running on the AT&T Network..
I’ve mapped out and gave the address to all the cell tower locations in the valley springs area I know of, so that will help you figure out where to point your phone or external antenna if you buy a device to help increase your cell phone signal.
Good luck! Let me know if you have any questions.