SPAIN

The cellular system in Spain offers FREE and un-metered airtime on all incoming calls. Local SIM cards are widely available. Prepaid local cards are available to any walk-in customer and can easily be purchased locally at network providers shops and authorized dealers. These shops are spread out in most of the main cities as well as central hubs – airports and train stations.

Reloading prepaid cards is also made very easy. Scratch cards with prepaid credit can be purchased in most any kiosk, convenience store, post office, etc.

Spain cellular providers and networks

Your cellular options in Spain

The following table maps out the various alternatives and their estimated costs.
All rates are presented in local EURO currency per minute

1 Estimated, may vary between providers
2 Ranges represent differences between local and international SMS
3 Ranges represent differences between peak and off-peak rates
4 Using the local SIM for local calls. Call setup charge applies 
5 Represented are the ranges of roaming rates offered by North American cellular providers

It just does not make sense to travel with a US or Canadian plan under the international roaming rates. Renting a local phone will probably turn out to be as big of a mistake. Buying a local prepaid SIM card is very simple but makes sense if used with a callback service. With both SIM and callback combined, local and international calls are made reasonable in price.
If you already have a local SIM card or if you are a frequent traveler only to Spain your best bet is to sign up for a callback service and use it with your local SIM. Note however, that you do not want to travel outside Spain with the local SIM card. Traveling outside of the SIM coverage zone will incur very heavy roaming charges that would make your calculated saving effort into an expensive money dumping experience.
For just about the same rates and savings you can set yourself up with a global SIM card. This global SIM card will offer similar savings in many other countries without roaming, so you can trot the globe with it and still benefit from the same great rates.
To have option of choosing your service and SIM card you need to have an Unlocked world GSM phone. Click the following link to learn more about ordering global SIM cards.