this is what I do. Costs me $0.05 per min for the call forward, and CAD$0.05 per min off peak or CAD0.40 on peak to receive the call rather than the $1.50 a min Telecom charges to receive a roaming call on top of the rate they charge people to call your cell. There is also a call back service where you call your number, then it calls you back and you make a call via 2talk. Can use this on your overseas cell to avoid paying $3.50 a min to NZ, or $8 a min to elsewhere!!!
(Canadian cell prices are weird, I could get a plan and have unlimited incoming calls but i just have prepay)