[Nexus 5 General] zivan56:
Many of you may be looking to test out different wireless providers with your Nexus 5, but the cost of switching may not be cheap. Thankfully, the Nexus 5 supports a nifty feature called "network camping." This allows it to "camp" on any network it supports without registering with it. Most phones can do this, but what makes the Nexus 5 special is the fact that it reports this network info all the way back down to the user. More specifically, it reports all the network info, including the signal.

Warnings

1. This will cause your phone to stop receiving calls until you undo all the steps

2. This probably doesn't work on Sprint registered Nexus 5s.

3. Make sure you write down previous values and switch the phone back, especially for step #2. If after this it still does not show a signal bar, go into Settings -> More... -> Mobile Networks -> Network Operators and select "Choose Automatically"

Step 1 - Remove SIM card

Removing the SIM card will trigger the phone to start scanning automatically.

Alternatively, you can go into Settings -> More... -> Mobile Networks -> Network Operators and select a network you cannot connect to (it should display "Your SIM card is not allowed to connect to this network" if successful)

Step 2 - Set the network type you want to connect to

Dial *#*#4636#*#* in the dialer (where you make calls). It will show a secret menu. Go to "Phone Information" and go down to the "Set preferred network type" dropdown. Select one of GSM only, WCDMA only, or LTE only. In short, GSM=2G, WCDMA=3G, LTE=4G. CDMA will not work, at least on phones that are not configured for Sprint.

Select the network types you care about. In generally, most providers globally require a fallback 2G or 3G network for voice calls. So, if you only have LTE coverage, you wont be able to make calls. So it is best to ensure you choose one that has at least a decent 2G or 3G network.

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Step 3 - Get an app that can read this information

Many apps that support the newer Android 4.2+ CellID API will allow you to read the network information. You can use CellMapper (which I have written), but you can use any app you want (I haven't tested with any others).

As a bonus, you can use CellMapper to map out cell towers and plot coverage for other people, sparing them the trouble of going through all this :)

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EDIT: I have updated the app to have signal bars,

Once you have the updated app (see screenshot below), you can ignore the signal mapping section if you want. However, I recommend reading it to understand how bars map to signal

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In the above, the app lists all the possible antennas your phone could connect to. Each one is called a "cell." The first one is the one your phone will most likely connect to, so you can ignore the rest. Generally, in urban areas, you will see dozens, whereas in rural areas you may see 1 or 2 only.

You will need to translate the "MCC" and "MNC" under the cell section to a network name. For example, Rogers in Canada is MCC 302 (Canada) and MNC (720) Rogers. Telus in Canada is 302 220. You can look this up on the following wikipedia page: http://en.wikipedia.org/wiki/Mobile_country_code. Just search for your country and find the matching MCC/MNC. Some other examples are 310 (USA) and 260 (T-Mobile), 311 (USA) 480 (Verizon)

Whatever app you choose, it will provide a signal level reading (in dBm). In the above screens, it is the large negative number to the right.

The dBm reading is essentially the signal strength/quality of the signal. Based off this reading, you can determine if you will have coverage or not.

dBm to "bars" mapping

dBm is translated to "bars" in the following manner for AOSP:

LTE

-95 dBm = 4 bars

to

-105 dBm = 3 bars

to

-115 dBm = 2 bars

to

-115 dBm = 1 bar

to

-140 = no signal

GSM/UMTS

-89 = 4 bars

to

-97 = 3 bars

to

-103 = 2 bars

to

-113 = 1 bar

So, in my screenshots above, I have Rogers reading -104 dBm for LTE (4 bars) and Telus reading -67 dBm (4 bars). Likewise, I also have WIND Mobile reading -81 dBM for UMTS (4 bars)

Step 4 - Visit the places where you want to test if you have reception

This part is easy, just visit places like underground parking lots, subways, etc in order to test out which wireless provider has the best signal to suit the places you most frequently visit.