The ATT version does not have this option based on the engadget review in which they tried to do this to check battery life. At least not on this stock firmware.
If you are not in an LTE area, you will get better battery life than if you are in an LTE area.
Sent from my SAMSUNG-SGH-I727 using XDA App
Nexus 5 (32GB), Moto X (32GB),
Lumia 1020,Galaxy S4 (32GB), Google Edition S4, S4 Active, Nexus 4, Note 2, Galaxy S3, Galaxy Note (ATT), Galaxy Note Intl., Galaxy S2 Skyrocket, Nexus S, Atrix 2, Atrix, Galaxy S1 Captivate, Nexus 7 (32GB)
and yes...an iPhone 5 too...