Dual sim card phones.

When I return home, I plan to get a newer phone. If I get one that takes 2 sim cards would I be able to have a local number in NV and use the service of my US provider?
I am reluctant to let me low cost US service go as I dont want to lose the number and since it is registered to a number of accounts, I think I might keep it going so that I can receive the security-check number they text when trying to log into some accounts. - @Dannyroc3

Get a Samsung or i-Phone as those are the two "preferred" 5-G phones on Viettel.

Yes, both the USA sim and the Vietnam sim will work, although the service you receive from the United States sim will be determined by the specific plan you have there.

@Dannyroc3

It is my understanding that dual SIM card phones have the capability to just toggle to the service one wants to use in the moment.

I'm on board to buy such a phone when I have to replace my current device. And we all know that technology doesn't stand still, so that day is not an infinite number of days from today. 🤪

I have a Samsung S23 and have 2 virtual Sims and and 2 physical Sim Cards including Viettel.  Just set your preferred card for calls, Data and texts. You can have 2 of the 4 active at any time.

When I return home, I plan to get a newer phone. If I get one that takes 2 sim cards would I be able to have a local number in NV and use the service of my US provider? I am reluctant to let me low cost US service go as I dont want to lose the number and since it is registered to a number of accounts, I think I might keep it going so that I can receive the security-check number they text when trying to log into some accounts. - @Dannyroc3

Get a Samsung or i-Phone as those are the two "preferred" 5-G phones on Viettel.

Yes, both the USA sim and the Vietnam sim will work, although the service you receive from the United States sim will be determined by the specific plan you have there. - @OceanBeach92107

One other possible option:

Since your phone number is already established with your bank(s), it's possible that you can port your number over to Google Talk/Voice and continue to use it seamlessly (one time $20 USD charge).

My experience: I was able to continue using my old established number with one bank after porting it, HOWEVER, when I then attempted to ADD that ported number to a different bank account it was rejected as a VOIP number without a mobile carrier.

Good luck!

@OceanBeach92107

I will likely get an Iphone that's a few years old, rather than spend a huge amount on a new one.

I was hoping my US (basic) plan through VISIBLE, would work when I am on WIFI in VN to avoid getting an international plan.

I would rarely use the US service so getting to wifi on those occasions would not be a problem, I just wonder if it will work through wifi.

I have the galaxy s24 Ultra which is dual sim but I dont actually use the 2nd sim slot. I converted my T-Mobile plan back home to an E Sim and I have my Viettel sim card in the physical sim slot. I use both sims at the same time. By default I have calls and texts set to tmobile and data set to viettel.