Sounds like a great trip! I'm envious of your footloose travels.

If your traveling abroad and your current wireless phone will not work, you're not alone. A hefty 50% of USA cellular telephones will not work overseas due to varying wireless standards used here in the USA. Many phones here in the USA, working with carriers such as Verizon, Sprint/Nextel and a few others have adopted wireless technologies such as TDMA (Time Division Multiple Access) that are unique to this country and do not have the required technology or necessary frequency to be used with overseas wireless operators. Now, if your US wireless carrier is T-Mobile or Cingular which works on the G.S.M. (Global Standard for Mobiles) technology and you have a tri-band or quad-band phone then it should work in many overseas locations. Usually, you must be a customer for more than 6 months and have an additional credit check done before the international roaming provision can be activated on your account. The reason for this policy is that call costs while overseas usually range between $1.29-$4.99/minute and most cellular customers talk 30% more while traveling on business. Also, with a GSM Blackberry or another handheld data unit you can surf the web and send and receive emails for between $20.00-$30.00 per megabyte. Do the math, these carriers can get stung for thousands if the average person chats and surfs away as if they were burning from their pool of minutes or unlimited domestic data plans which is why personal credit becomes more important to your carrier.

The simplest and most cost effective way to roam across the globe is by renting an international cellular telephone or Blackberry from providers who specialize in temporary international phone service. International phones usually rent from $25.00-$50.00 per week and commonly have rates lower than even the USA GSM carriers roaming rates including free incoming calls in many countries. Also, you can buy a world phone for between $60.00-$300.00 that can accept a prepaid international SIM card (Subscriber Identity Module) that can be used in single country destination only. These prepaid SIM cards work well if you are traveling to a country where English is the primary language, otherwise all of your voicemail and other prompts to recharge the SIM with your credit card will be in the destination countries language and that can be more than a little overwhelming.

There are also more and more WVOIP (Wireless Voice Over IP) offerings for the person travelling with a laptop or Symbian phone that has a Skype or similiar account. WVOIP is in it's developmental infancy so although you can make and receive calls for pennies from major world cities the service quality and coverage will be poor at best. Whatever option you choose it is always prudent to read the fine print for taxes, activation fees, network access fees, set up fees, etc.. A shrewd traveler should be able to save big and have great coverage with a little research and web shopping prior to their departure date.

I dug around a bit to get specifics and there are indeed a bunch of companies that rent out cellphones that will work throughout Europe, including Global Cellular Rental, Cellular Abroad, Rent A Cellular Phone and Phone Rental USA. All of them seem to make your life easier, however, by letting you rent them before you get on the plane, which seems like it'd be far, far easier than trying to rent one once you get to Spain.

Global Cellular Rental, for example, explains that they offer seamless wireless voice and data solutions for the international traveler, providing local wireless phone numbers across the globe. They claim that they can usually save customers 80% compared to their T-Mobile or Cingular international roaming rates (other US carriers have phones that are incompatible with the European GSM standard).

Like most of the rental firms, GCR covers every country in the world with GSM phone services and if you are going to be in areas where there's not likely to be any cellular coverage, they also offer bulky Iridium hand held phones, about the size of a cordless phone (pictured on right).

Iridium phones work anywhere on the globe as long as you have sky above you and rent for $99.00 week. Incoming calls are free, outgoing calls are $1.89/minute for direct dial to anywhere in the world from anywhere in the world. Local number GSM phones rent for a reasonable $5.00/day, incoming calls are usually free and outgoing calls cost between $0.89-$1.50/minute depending upon the destination.

Global Cellular Rental deliver phones anywhere in the USA for $10.00 and there are no other fees whatsoever. All international charging adapters, dialing instructions and accessories are of course included with the rental kit.

I presume other companies offer similar deals, but I have to say that $5/day and free incoming calls sounds like an exceptionally inexpensive solution to your dilemma. I'll close by wishing you a very safe and happy bon voyage!