How to improve standby battery life on your GSM HTC EVO 3D

Note: If you're in the USA and on Sprint, then this most likely doesn't apply to you.

If you have a GSM HTC EVO 3D and have been noticing fairly high battery consumption while in standby, there may be something you can try to fix it. I say "may" here because I have a CDMA EVO 3D and can't test it out for myself.

However, the world doesn't revolve around Sprint and I know there are some GSM users out there who deserve some dedicated G&E attention. 

Before you proceed, please make sure to write down anything you change just in case the following procedure causes your EVO to stop functioning properly. Having your old settings handy should let you go back in and change anything back without much effort. Ready?

• Dial *#*#4636#*#* but don't press call/send
• Press "phone information" from the menu that appears
• Select your preferred network type (you can call your carrier or check Google to find this out for your particular location)
• Go back to the main menu 
• Press "menu" and choose "Select Radio Band"
• Select the appropriate band for your location
• Make a test call to ensure you still have the ability to call someone

The theory behind this is that your phone uses less power by not attempting to communicate across several different bands while it is idling. This mod changes nothing while you're actively using the phone; it's for standby only.

There's only one CDMA band used in the US (Verizon/Sprint), which is why this tip is for GSM users.

[xda-developers] Thanks, Amace04!