advice and opinions pls:- which is most battery effecient smart phone for SIP/VOIP

[Guest Just Wondering]

hi , i'm currently running a zte blade (rom 2.3.4) great little phone , but i'm finding the bulit in sip application heavy going on the battery.

I'm happy to buy another phone or a cheap older 2nd phone , but what in peoples experinces have been the most reliable smart phone for sip connection (incoming calls) and battery efficient , or is there a very battery efficient app for andrioid that wont drain my battery on 3g or wifi quickly ?

i'm finding on wifi i lose around 5 percent a hour when setup for incoming sip calls , and around 12% a hour when setup for incoming on 3g.....

i run my sipgate connection through pbxes.org which i'm told should make things a bit more efficent , does this mean i can lose the stay alive connection ? would this save battery if i lenghten the time on this ?

Help and advice most welcomed ;)