^I agree with being cautious for this kind of thing but you do realise we do have strong privacy laws enshrined in our constitution, be careful your not being too paranoid!
Unless your some kind of big dd, or dealing with some big dd the authorities have absolutly no right to listen in/record what is being said, plus do have any idea of how much it would cost in monetary terms and man hours just to sting all the small scale dd's out there. Coppers are after the big fish, the ones they can proudly show on the evening news.
The problems more lie with sms's. If someone big does go down and your connected to them then they can do a 3 yr sms history search easily, and thats how you get fucked!
For phone calls they may have the technology to listen, however, unless cops recieve a court authorised warrent then they cant use any information learned from your conversations with your dd. We are living in a police state where erring on the side of caution is a good idea, however, we are protected by our constitution and basic democratic principlas of freedom which don't allow authorities to go tapping phones and screeing our email... be careful not paranoid!