SIM card

The SIM card doesn't have anything to do with your contacts or apps. You should be able to see them just fine, even without any SIM at all ( or one bought in Uzbekistan). You just won't be able to call any of them (or anyone else) without a SIM that works where you are.

The contacts and apps don't really have anything to do with what SIM you're using. However, when you get a new SIM, it comes with its own phone number. Some apps and/or settings (eg Uber, text messaging apps, etc. - anything that is associated with your "regular" cell phone number) will need to be updated to correctly point to the new phone number for your new SIM. There can be a potential catch-22 with updating that (you may need connectivity to do the update).

But your contacts and apps don't vanish when you swap in a new SIM.

It's a valid question, because SIM cards were originally used to store your contacts - on flip phones, before smart phones were popular. These days, everything is stored on your phone itself and synced (most likely) to an account like your Google or Apple account.

Just swapping out your SIM card shouldn't affect your contacts or other stored files anymore. You can use your phone without a SIM card - on WiFi. Turn your phone off, remove the SIM, and turn it back on and see how it works without the SIM. You'll likely get a message warning you that you don't have a SIM card in the phone, but you should still be able to everything besides calls and texts as long as you have WiFi. If your phone supports WiFi calling, it may even still let you do calling and texting on WiFi.

I greatly appreciate your replies, puts my mind at rest. Mary.

Andrew, I read your write up of your purchase on ebay. I will plan on going this route, but wait until nearer to my Nov travel date because the card needs to be topped within 2 months of purchase date. Thanks for your information - looks like the easiest way.

Roger, where did you read of the "two month" requirement? I've never never heard of it. My SIM came in a sealed envelope (Vodafone packaging) and had an expiration date on the back that was more than a year out.

Mary,

Although your contacts will still be in your phone, you may need to activate the "Country Code" feature in your address book. For USA/Canada, the country code is "+1." For Spain, it is "+34." So, in order to call or SMS text a contact in the USA/Canada from your phone when using your SIM purchased in Spain, you'll (probably) need to add the country code to that phone number.

Mary,

Sorry, I didn't notice you are from New Zealand. In case you're not familiar, New Zealand's country code is "+64"