How to Use SIP (to Save Money)? europe.

hi all,
hope it helps others too
to save money...
is cheap or free phone call to cellphone possible?
just stumbled over MicroSIP Portable and think it could help save for mobile calls.
wire incountry callas to mobile are here xtimes you pay to mobile to other country. europe.
would be livesaver as online sms not working ever!
thanx for any ideas/tips!
maybe you are even from DACH space and know something that helps.
propably @ottosykora?
please don't kick me, it's in offtopic.