Hello,
The simplest option you have is to use your Hawaii cell phone while in Spain. In this case your phone number stays the same and you can answer calls as you usually do (for example, people from the US don’t need to add any international codes to reach you); of course, you’ll be the one paying the international charges for calls received. This is obviously the most expensive option (you’d have to ask your wireless provider about rates, but they are generally high, especially that, in order to communicate between two US cell phones both in Spain you would pay double the international roaming charges). One other thing with this option – most European wireless providers use the GSM technology. You would have to make sure your phones will actually work in Europe as some US networks do not use GSM.
One other option would be to buy Spain prepaid wireless SIM cards locally and either use them with your current US phones (if they work with GSM technology) or buy some inexpensive basic cell phones. Calling rates are usually reasonable for Spain domestic calls plus, depending on offers currently available you’ll probably be able to talk free when calling other mobiles in the same network (or when calling outside peak hours). Some prepaid plans also include international minutes – make sure you inquire about this, also what rates are charged when calling the US. One good thing about European cell phones – you do not pay to receive calls. Here are two big Spanish wireless providers:
https://www.vodafone.es/
https://www.orange.es/
Regarding how you will dial: in Spain just dial the numbers they dial with either of the two options described above. For example, Spain cell numbers are 9 digit and start with 6 as follows: 6?? ??? ???. To call the US add 00 to the Hawaii number: 00 1 808 ??? ????.
