I've been doing a lot of research on SIM cards recently, trying to figure out whether I should buy an extra phone and an international SIM card, or bite the bullet and pay for Verizon's outrageous international fees. But then I came across a post here talking about dual SIM phone. It turns out they are fairly common in newer phones and allow you to add an extra SIM card into your phone that can be used interchangeably with your regular provider's SIM card.
Those sounded pretty cool so I checked, and my iPhone 11 mini does not have the dual-SIM capacity. However, the technology has advanced and it turns out that most newer phones (post late 2017) have eSIM capability, which is basically a digital SIM that is soldered directly to a device's board, and is remotely reprogrammable through software. Basically, I have the ability to use two different cell phone providers. In my phone, Verizon uses the physical SIM card and the eSIM slot is available for another cell phone provider (either the same one, another US one or an international provider). It is mostly used by people who have 2 phones - one for work and one for home. Having the option of a second SIM (hard or eSIM) allows someone to use the same phone but switch back and forth from one carrier to the other.
I found that people on the forum who have used the eSIM switched their main provider to the eSIM, and then bought an international physical SIM card. So for example, since I have Verizon, I would need to switch Verizon to the eSIM, which from everything I have heard, may be easy or could take hours, depending on the person you talk to at Verizon. But instead, I can keep Verizon on my physical SIM card, and use the digital eSIM data plan for the other line.
It's a pretty easy process and there is no need to swap out your SIM card on your regular phone or buy a burner phone or use an old phone. You just carry one phone and switch the SIM back and forth. I am planning to use this process for the one month trip to Germany in late April but in the meantime, I have found a lot of resources, so I thought I would share all this information I have in case anyone else is interested.
I don’t know about other phones but if you have an iPhone, you can find out if you have this capability by going to Settings>General>About, then scroll down to the bottom. Under “Physical SIM” you should see your network/carrier listed, along with a string of codes and numbers (IMEI, ICCID, and MEID). Below that, it will say “Available SIM” and have a separate IMEI2 number. I believe that all iPhones from XS and forward have this. But again, the phone must be UNLOCKED.
This website gave me information about the process and how to find an international eSIM data plan. He describes how it works in detail and tells you how to set it up once you've bought the data plan (along with links to sites with detailed steps for iPhone, Samsung, Google Pixel, and Huawei phones). https://travelwithbender.com/travel-thoughts/travel-tips/international-esim-travel
Information for iPhone users: https://support.apple.com/en-us/HT209044
Information for Verizon users: https://www.verizon.com/support/esim-activation-instructions
One international eSIM plan that was recommended by the Travel with Bender article. https://esim.holafly.com/esim-europe/
Also, here is a link to an Orange plan that a Redditor used and liked. At the bottom, you check a button to indicate if you want a physical SIM or eSIM. https://travel.orange.com/en/detail-all-inclusive/?geozone=EUR&ref=orhldeur20gb
UPDATED to include this Reddit post with a list of eSIM data providers as of Dec. 2021. https://www.reddit.com/r/eSIMs/comments/rrh488/state_of_the_market_list_of_esim_providers_as_of/
UPDATE: This post by Holafly gives a list of ALL phones with eSIM capability (as of July 2022). https://esim.holafly.com/how-to/esim-phones