Apologies about my first post, i probably wrote it on my phone in a hurry. Basically my network transmits 2 bands of 3G in built up areas, 2100mhz and 900mhz.. In lesser populated areas the towers only transmit 900mhz...
I'm guessing my network doesn't have a lot of space on the 900mhz band so the network makes sure my phone stays on the 2100mhz band at all costs. Unless the signal goes very low on 2100mhz my phone as a last resort will then connect to the 900mhz band. The result of this is I could be standing right next to a 900mhz tower but my phone would rather stay connected to a 2100mhz tower some miles away which could have only one bar of signal when i should be enjoying full clean signal. Not good for battery life and possible missed calls. Of course toggling the airplane mode forces a connection. I just thought if that is controlled in the carrier file that a tweak could make my phone not discriminate the 900mhz band lol.