In the Google Voice app go to settings, make and receive calls, Prefer WiFi and Data (checked). I have made and received GV calls with no issues when using an international sim when traveling in Europe and Asia. The default is often set to Use Carrier which does not work when using a non US sim.

If you are going to travel internationally a significant amount, my recommendation is to get the Tmobile plan which gives you free text and 3G data. The plans are more expensive on a per month basis - I pay $60/month - but you have zero ($0) cost to automatically get the above when traveling everywhere that I have been: Europe, Asia, Central and South America, Japan, Russia. Canada and Mexico both work fine too.
There is a $0.20/min fee for receiving or initiating voice phone calls. This is fine since you have full control over either plus can avoid if you WiFi call (see below).
I've been a Tmobile customer ever since they merged with Sprint, but I think the modern version of the plan is called Magenta. It also includes a Netflix basic subscription, WiFi calling, free in flight internet/texting on a number of airlines including United.
Tmobile also allows iPhones at least to be used as hotspots for laptop based email.
I see there are 55+ versions of Magenta, so may be even cheaper than what I am paying now although my actual plan is a legacy one equivalent to Magenta+.
If you want/need greater bandwidth than 3G, you can either get the higher bandwidth options (4G, 5G) permanently or pay for passes to temporarily increase bandwidth. A 10 day pass is $35.
With this plan, there is no need for juggling phone numbers for people to contact you, or to recharge a sim, or to get a sim (which is increasingly more difficult in the West).
And finally: you don't have to worry about Google spying on you, either. I will never use a Google service: basic Android, gmail, Chrome, or even search if I can help it.

I've used Google Fi for years internationally without a problem. I also use Whatsapp on wifi to talk to friends and family. It's free and the sound quality is excellent.

US Mobile released some updates to their plans yesterday - including updating their "Unlimited Premium" plan to include 10GB of international roaming data in 100 countries (plus 500 minutes/1000 text), per billing cycle. That's in addition to the 100GB of high-speed data (50GB hotspot) that plan offers domestically. This is only on their "GSM 5G" plan, which is T-Mobile based and costs $50/month (their equivalent "Warp 5G" plan which is Verizon includes international data, but it's done using eSIMs that you need to obtain before use so it's as clean).

Likely not the cheapest option, but a fair compromise for unlimited data in the US, and a reasonable amount outside, without having to use eSIMs.

I've been using US Mobile for about 4 months so far, and haven't had any problems with them. Their website/app are good, and service seems fine (although I'm on their Warp/Verizon plan not the T-Mobile one at this stage). They do have a referral program, but as the person being referred doesn't get anything out of it I won't post it here. DM me if you want a link...

Another long time T-Mobile user. Travel extensively. Switched from ATT more than decade ago!

I signed up yesterday for their WARP 5G $10, 2Gb Unlimited Talk & Text plan. It includes all fees & taxes and was a pretty easy process. It is a sharing plan and you can add additional lines for $8 each. I chose this mostly for having the option to switch to Verizon in the rare instance when my T-Mobile service becomes spotty. I used to have the Xfinity cellular for two lines at about $19 a month, but only 1Gb of data on our two main lines. It was also Verizon service. I am impressed so far with the US Mobile organization, and their setup. There is no commitment and as for the $10 a month, I spill more than that, LOL. They have a pretty decent app, with a good layout that is easy to use and understand. Seems like a pretty squared away organization.

I wanted to have this in place for my iPhone 15 Pro Max as an esim to transfer today when I do the setup from my current 14PM to the new phone.

My US T-Mobile plan gives me data and voice in over 200 countries. The speed is generally fine, but I also usually download offline Google Maps data fr wherever I go. There have been very few places where I didn't have service and I purchased a local SIM card, but those were not places most people would travel to. I've got an older plan where I pay $17/line/month + taxes.

I've been exploring the US Mobile plans since enrolling in the "Warp 5G" service a few days ago.

They have a nearly perfect travel plan based on T-Mobile domestic service for $50 a month (Plan is GSM 5G, Single Line=$50, 2=$90, 3=$120) inc. taxes & fees. It includes 100Gb of 5G high speed data & 50Gb of hot spot in the US. The place it really shines is in the included international features. You get 10Gb of high speed data, 1000 texts, and 500 minutes of calls in 102 countries around the world per billing period. Oddly, the 500 minutes of calling does not include calls to the US, but I think WiFi and IMS functions are easy and practical for those calls.

They have sim cards and esims, and a decent phone app. The web site is easy to navigate and use for info and account details. I must say, if I didn't already have T-Mobile with grandfathered roaming service, this would be a serious contender for domestic and travel cell service. I have only contacted customer service once, but comments are generally quite favorable on Reddit from current users.

These features were introduced around 9-20-23, so take a look if you haven't been there lately.
https://www.usmobile.com/

Edited to add: In backtracking this thread I discovered I had duplicated docbert advice with my posting about the recent version of US Mobile's plan for travel. I apologize to the community and especially docbert for this faux pas on my part. They say never ruin an apology with an explanation, so I'm sorry for this apparent plagiarism.

Just want to report back so far on my poor man's solution: iPhone 11 + Tello voice/text only + various eSIMs (Eskimo, 3 HK and ChungHwa Telecom in Taiwan).

It seems the 3HK eSIM is kind of slow but it works - can't beat the price 1 year 30 GB + 5 GB for social media for about US$35 (US, Canada, NZ, AU, UK and HK). The Eskimo one seems faster even though it is farther (in Singapore) relative to North America. Yes, I get a HK IP.

Tello has worked well for me. I just use the $7/month 500 minute plan with no data. When I am outside the US, with Wifi Calling enabled, it says Tello over Cellular Data (or Wifi if I have Wifi). The good thing is they don't have roaming so I don't have to worry about accidentally racking up roaming charges.

The big thing with Tello and I guess with any carrier is that iPhone Visual Voice Mail requires a data connection. So, it is back to voicemail the old fashion way.

By the way, I still have the legacy T-Mobile PAYGO. I was able to add $1 and extend the validity by 1 year!

Got an e-mail from Tello this morning and they now supports International Roaming. However, data-only eSIMs still come out much cheaper.

I have been using TextNow for the last 2 years to be able to get text codes from my banks in the USA. I'm a US citizen who lives in Australia. I use WhatsApp for 99% of phone and texting and I have a local Australian SIM card since I live here. TextNow shut me down for using the service overseas. All I need is some kind of app-based US telephone service that allows those short text codes banks send to verify you.

I have heard of Tello. Before I sign up, can anyone confirm it works with B of A and Chase? Other bank data points?
And they won't shut you down if you are overseas?

Friends who moved to London (they intend to stay there permanently) ported their US numbers to Mint Mobile before they left, and let the Mint eSIM use their local UK eSIM's data connection.

I just got back from a month abroad and beta tested Popcorn Mobile from Portugal down to South Africa and in Istanbul. The only two countries it didn’t work were S�o Tom� and Namibia.

Otherwise, it worked like a champ. They don’t cut you off for extended time abroad. My wife and I are toying about retiring to Portugal. So far so good. In the US it uses both TMobile and ATT. In addition to your regular eSIM, they give you a secondary data SIM. In the US, I would put the secondary SIM in virtual slot 2 and use it for fallback roaming. In Europe, I would have a voice only Portuguese SIM in the other slot. Popcorn.io.

That website demands a login before it will load. It appears the correct website is popcorn.space. There is also a popcorn.tel, which seems to be a Russian mobile operator offering very similar services. It isn�t clear to me whether the two are related.

One oddity that makes me suspicious is that popcorn.space�s domain registrant details are redacted in the public Whois. Doesn�t seem like the kind of thing a reputable company would do, so it makes me wonder if the Russian company owns the US one and is trying to be sneaky. I would use a different carrier, personally. I don�t want all my communications being routed through Moscow�

I'm in almost the same situation as you (ex-US resident who's now in Australia). I use US Mobile, specifically their (no longer available) $5/month plan. This gives 500 minutes, 500 sms, 500MB per month, but most importantly it does NOT support roaming, but DOES support Wifi calling. So whenever I'm in Australia it'll work by using either my wifi connection, or my piggy-backing data over my local Australian SIM card (what's called Backup calling on Pixels). No issues with using the service overseas - it doesn't support roaming, so won't even connect to a non-US mobile network directly!

This worked perfectly for me for both SMS (including banks/etc) and voice calls, both in and out. The only catch is that they no longer offer this plan, and the equivalent one is now $10/month although it does include more minutes/data. There's a few other providers that have similar plans for $5 (eg, Hello Mobile) although I can't specifically recommend any of them.

It used to be possible to pay for additional data for a month for times when I am visiting the US, although they seem to have recently removed this from my grandfathered $5 plan - although it's still possible on the new $10 equivalent.