It's worth doing the research on which provider offers the best rates for calls to mobiles wherever you will be traveling. I agree that forwarding to Skype can be unreliable, I've had many cases where I thought I was logged in on my mobile only to find that it had disconnected itself.

VoIP.ms, Callcentric and Flowroute are all good options, in addition to skypeout. I've been pleasantly surprised at how competitive some of the Skype rates have become, particularly for calls to mobiles.