mev

Agree with this.

I'd probably simplify this to say - if you plan on using a using a local sim, make sure you have an unlocked phone.

Carriers like Verizon have typically sold phones that are locked to their networks. However, this isn't unique to CDMA as carriers such as AT&T also sell phones with sim cards locked to their GSM network. Also Verizon also has a "bring your own phone" - https://www.verizon.com/bring-your-own-device/ approach for their network.

There used to be more of a distinction that most CDMA phones were sold locked (or without sim slots) and most unlocked phones were focused on GSM. However, that has become less over time and the distinction between CDMA=locked, GSM=locked+unlocked has become less true than it was before - at least in the US.

Tourist in MSN

As far as I know the practice of phone companies locking phones to that company cell plan was a USA thing. Perhaps also Canada too?

But I think that Europe did not follow that practice, it is my understanding that people bought their phone and separately signed up for a cell plan.

Asia, I am clueless on that but I have assumed that they followed the practice set by Europe.

I am a natural cheapskate, I bought an unlocked Android phone five years ago for $105 (USD), I pay $10 per month for a very minimal cell plan that has no international option. But since I use my landline when at home, a minimal cell plan is perfect for me as my cell phone is almost exclusively used for travel and not much for local usage.

DangerousDanR

I have a Google Fi phone, so I have cell service in Canada. Several years ago my wife and I had a truly weird experience that our daughter in the US could call us, but we could not call back. We could send text, however. We couldn't find a remote B&B where we were supposed to stay that was well north of Winnipeg, and we couldn't call the people there to ask for directions.

But we could text our daughter, she called the people, got directions, called us back and got us to the correct road. Then she called the B&B and they met us at the road. Much better to have the Fi, since it works in both the USA and Canada.

Tourist in MSN

That is one reason that I have Google Voice on my phone. I previously made this comment.

Basically I can use my phone like a regular phone when I have an internet connection. I have a phone number associated with my google voice plan and people can call me when I have an internet connection, but when I travel I almost never have an internet connection so that is why I tell people that they can't call me on that number.

I can get voice mail when I have an internet connection, their voice mail is sent to me as an attachment in an e-mail.

I do not know if signing up for Google Voice is still limited to customers in USA or not but it might be. But once you have it on your phone you can make calls anywhere that Google works on the internet, meaning I think it does not work in China.

Using Google Voice I called one of my credit card companies from Budapest when my credit card quit working, called using the hotel wifi. I also called a different credit card company from Reykjavik when that card quit working, I got that card turned on again by using the hostel wifi. I have used it in USA in an area where there was no cell service for either ATT or Sprint, but the restaurant had wifi so I could make motel reservations. Only once did I call someone in a foreign country with it, I was in Reykjavic and I was not sure how to make a call to a foreign country so I asked the receptionist at the hostel if I could call her to test it, and yes it worked, we had a short conversation. There is a small fee to call a foreign country, and even though I was in Iceland when I called to someone standing 10 feet from me in Iceland, I was charged that small fee, which was just fine with me.

If I had a data only sim card with no voice plan, I could use that data plan with Google Voice to make phone calls too.