I have a problem with receiving calls and text messages due to a weak 3G signal, now I want to make my phone and force it to work on the 2G mode only, but since I am on lollipop 5.0.1 I don't have this as a choice. I tried using this code: #*#*4636#*#* but it doesn't work with me. I also tried a few apps from the play store (e.g. Toggle Network Type 5.0 which was specifically made for Lollipop) but nothing works.
My phone is rooted.
Some Samsung devices require root access to launch the hidden testing menu. The normal code will not work in the dialer; even with ADB, you don't have access to the menu.
Since you have root access, just type the following in a terminal on your phone and the hidden testing menu should appear:
su -c "am start -n com.android.settings/com.android.settings.TestingSettings"
It may be easier through my app Root Essentials that can do this and more. You can find that test menu under "Device Info".
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