@KanagaDeepan what I'm trying to say is that even if reliance network throws up 2 bars, automatic mode would seldom shift to Aircel (even though Aircel is 5 bars) unless we manually set it. Probably because every second/minute that a client is on Aircel network, they bill Reliance. So Reliance avoids it, & have done individual network sharing/coding at each tower accordingly.
In my personal experience, Rel GSM jumps to Aircel only if the network is heavily fluctuating or goes down to 0 bars. To avoid all this, I have permanently set my network to Reliance, at least while in Bangalore.
As another example, so many times while using HSD cards also, i have noticed that HYBRID mode performs poorly especially where HSD signals are a bit weak. But strangely, keeping it in HSD mode manually, does better.