I'm sorry to tell you that Skype Online Numbers are not available in Spain. So, that is not an option for you there. Skype Connect is offered in Spain and we can connect to your PBX or SIP device at anytime. You can than make calls all day long using a Skype Connect SIP Profile. The cost will depend on where in the world you are calling. The cost is on a per minute basis (subscriptions are not used with Skype Connect) and the only additional thing you would from Skype would be SIP Channels purchased on a monthly basis, to connect our PBX or SIP device to Skype.
If you intend on using a Mobile Internet service, the cost could be quite high as Skype uses a lot of data to maintain its connection. If you continue to use your current Skype Client, that might be the way to go for now. It is still cheap and available every where in the world, and you can take it with you on your mobile.
I have added a few links to Skype Connect and the Online Number Plan below.
Thank You for using Skype and the Skype Community Forums.