Hey I have a nexus s device which runs on the 3g 900/2100 mhz networks as well as the gsm bands. My problem is that my phone is set by default to have a preference for the 2100mhz frequency, whenever it picks it up it changes to that. But there is very bad signal of that frequency in my house, and so my phone keeps jumping from 900 to 2100 back to 900 and so on and drains my battery as well as making internet browsing infuriating. Is there an app or anything at all that I can install that allows me to set a preference for frequency? Like a use only 900mhz option?