How can I get a Galaxy S4 to run in 2G?

[yawg07]

My friend wants to be able to run his Galaxy S4 in 2G mode but nothing we try is working.
He has Android 5.0.1 and no guides seem to work for it.

I tried the *#*#4636#*#* on my Galaxy S6 Edge running 5.1.1 and it worked like a charm.
But when input on his phone, absolutely nothing happens.
Can anyone help?

 

[wcjeep]

Is this to conserve battery power? Turn data off. Call/ text will still work. It will go to 3g when available. Should use less power and consume no data. Best option with S5 and above ultra low power mode.