SIM cards for non-residents?

you can still do a monthly prepaid  I use Vietel 135k  dong for 5g and 5gig a data

For previous visits of up to 15 days I've just got a form of tourist (physical) SIM card. I'm curious about what longer term visitors' solutions are if they're not officially resident and so can't obtain a regular contract. - @It2VN

Without getting into the ins and outs of phone vs data vs phone/data plans, a foreigner only needs a legal visa, a valid passport valid for 6 months after visa expiration and a legally registered temporary address.

For those staying in hotels & motels & apartment buildings, a check-in receipt from the lodging is usually sufficient, but having a copy of their Form NA 17 "declaration of temporary residency for foreigners" would be best.

Most foreigners never see this document: The landlord (technically your temporary sponsor) fills it out and submits it to the local police for approval. it's a nightly ritual in hotels and motels and hostels, even those where people only stay one night.

Unfortunately as you may very well know, many foreigners obtain cheap lodging from homeowners who don't ever register them legally. The landlord can get away with it for various reasons, for various lengths of time.

It's those people who truly aren't legally registered residents of Vietnam that can't get a registered SIM here

Thanks for the feedback.

I'll try the check-in receipt route first and if that proves problematic, I might as well go the monthly 5GB or similar option. Depending on how things pan out, I'll probably be looking to do visa runs or just return after visiting other S.E.A countries on recces.