双卡双待怎么设：本国号码收 OTP，流量走 eSIM

Yes, as long as the line itself stays switched on. SMS travels over the network's messaging channel, not over data, so what stops codes arriving is switching the line off, not switching its data roaming off. Note that some services deliver codes through an app or by email instead, and those do need a working data connection. If you are unsure which method a service uses, test it once before you travel.

The most common cause is automatic data switching, which moves data to the home line when the eSIM signal weakens and moves it back again without telling you. The second is data roaming that was only partly disabled, since some phones keep separate switches at line level and device level. The third is calls made or received, which have nothing to do with data at all. The itemised detail has to come from your home carrier, because only they can see what was actually billed.

There is no single right answer; it depends on which need is larger. If you still have to take calls from work or from a bank, keep the Thai number as the default for calls and messages and let the eSIM do nothing but data. Most phones separate the two choices, letting one line handle calls and another handle data. If your handset cannot separate them, choose based on which loss would hurt more.

You can change them at any time. These are operating-system settings, not something bound to the plan's activation, and moving the data line back and forth does not damage the plan. The one thing to avoid is deleting a profile, which is usually irreversible. To stop using a line for a while, switch it off rather than remove it.

The option does not exist on every model or every OS version. If it genuinely is not there, the most direct substitute is leaving data roaming off on the home line: even if the phone switches to it, it cannot pull data from a foreign network. The alternative is turning that line's mobile data off entirely for the trip while leaving the line itself on to receive SMS. Both get you to much the same place without relying on a switch your phone does not have.

Recent handsets generally store several profiles but can keep only a limited number active at once, and that limit varies by model and OS version. The safe pattern is to keep every profile installed but enable only the one you need in the country you are in, leaving the others switched off. Check your own handset's limit before buying several plans, since the number that can run simultaneously is not the same on every device.

If the bank sends SMS, yes. If it uses an in-app prompt, that runs over the eSIM's data, which also works.

The home SIM is still registered so it can receive calls. With data roaming off, no data charges accrue.