based on comments/discussions in -> A guide of how to turn OFF evdo on your 815 THANK YOU TO ALL THOSE WHO HAVE CONTRIBUTED!!

This page instructs you how to disable EVDO on your E815.

Why do this?  The phone uses EVDO for data services only, in some areas, EVDO is not completely rolled out, or there are "fringe areas".  As the phone switches between 1x and EVDO modes, it can drain the battery faster.  Disabling EVDO (or forcing the phone to 1x mode), can and does help this.

NOTE: VCast requires EVDO, however, other than being "slower" this fix does not harm anything.

NOTE: Do the wrong thing in test mode and you will mess up your phone!!!

NOTE: this must be re-done if you do a *228 opt 1, or *228 opt 2 on your phone!!

The process...

Enable Test mode...
   MENU 073887*
   for security code enter 000000
   press OK.
   arrow down to test mode...
   press select.
   Highlight Enabled and press select.
   Press END to exit out of all...


Press the center Menu key quickly followed by the left soft menu key.
You will be brought to a white screen with a "blue" FTS in the top center.

Press the right soft menu key 3 times to get the the screen with ServOPT: at the top... and HDR PREF as a choice.

use the down directional arrow aprox 5 times to select HDR PREF...
Press the right soft menu key to change it to CDMA.  NOTE: phone may become unresponsive for a few seconds...

OPTIONAL: use the down directional arrow once to select HDR Hybr: and press the right soft menu key to change it to OFF.

Press the center Menu key quickly followed by the left soft menu key to exit you out.

Disable Test Mode...
   MENU 073887*
   for security code enter 000000
   press OK.
   arrow down to test mode...
   press select.
   Highlight DISABLE and press select.
   Press END to exit out of all...

To Re-enable EVDO,

use the same steps, however set HDR PREF to "auto"