<p>First of all, there is quite a bit of misinformation here. The iPhone will NOT be unblocked by the US company. The older versions of the IPhone might have safeguarded the right settings to be jail broken and unlocked. The chances that this will happen on a newer model such as 3GS and 4 are slim to none. </p>
<p>In so many words, you cannot expect to purchase the SIM card in Spain that will work on a newer IPhone. That is why it is better to purchase a local throwaway phone. </p>
<p>On the other hand, the IPad is unlocked by default. This means that the Microsim that does NOT work in the IPhone will work in the IPad without a hitch. </p>
<p>The next question will be to purchase a contracted Sim or a prepaid one. A four month stay might be cheaper with a contract, if a local can help secure a contract. Data on a prepaid tends to be expensive in Spain.</p>
<p>One last option is to purchase a MIFI modem that works with the 3G network. This will make both the IPad and the IPhone work for Skype calls - not cellular. Also, it is possible to buy a USB dongle to connect the Mac. </p>
<p>Search for the older threads on CC. This issue has been discussed at length.</p>