Connection error- N91, and battery life

Question

I have been using Nokia mobiles for the last 10 years, usually with Orange, but now switched to O2.
1. Had the phone a week and when in conversation with someone the call just drops - done this a few times. The signal is still on maximum. Anyone had a similar problem? not sure if its network or mobile. Im guessing its the phone - just get a "connection error" message, and sometimes does not even let me ring the number again.
I turn phone off and on, then everything works fine. Very strange.
2.Battery life. Ive heard a few people moaning about the N91's battery life. I never thought it would be this bad. I have to charge it up every 20 hours with the following usage:
* 2-4 phone calls of no more than 5 mins
* 2 pics camera usage
* 50 or so MMS
* no music player
* bluetooth connection to headset for one hour in total
My 6230 despite the fact ive had it for 2 years, still lasts for about 4 days without a charge.
Im travelling overseas soon (for work) and there is no chance i will ever get of charging the phone. So with mild usage my phone is just going to run flat. I have spare batteries, but this is just inconvenient.
AS this phone has a hard drive I would of expected Nokia to develop a battery that can cope with this. But obviously not.

Answer 1

If you've got the network mode set to dual mode, it should be able to switch flawlessly from GSM to 3G and vice versa depending on the signal available at the time. If you don't uses video calling, you might want to go into Menu, Tools, Settings, Network and change the network mode to GSM only - that way you should be less likely to drop calls due to this switching.