eSIM versus roaming is a choice between two ways to get a mobile signal abroad. An eSIM lets you add a local or regional data plan to your phone without a plastic card. Roaming keeps your home SIM and your home number, and your own operator bills you for the extra use. For most business trips in Asia, use roaming for calls and a short stay, and add an eSIM for data on longer or heavier trips.
This guide compares the two on cost, speed, your phone number and phone support. It is general information, not a recommendation of any provider. Check each operator's current terms before you fly.
What each option is
An eSIM is a SIM that is downloaded to your phone instead of inserted. The GSMA, the global body for mobile operators, explained the technology in a March 2018 whitepaper. It describes a chip inside the device that can hold more than one operator profile. The profile is sent over the air, often when you scan a QR code supplied by the operator.
Roaming is the older route. Your home operator has agreements with partner networks abroad. When you land, your phone joins a partner network and your usage is billed to your home account. Operators in Singapore, such as Singtel and M1, sell roaming passes you add to your existing line.
The GSMA is clear that the eSIM does not make roaming disappear. Its whitepaper says remote SIM provisioning will not replace the roaming services that operators provide.
Cost: pay for what you use, or pay a flat fee
The two options are priced in different ways. We compare the structure here and leave out prices, because they change often and differ by country.
Operator roaming usually has three levels. The first is a daily pass, which covers one destination for one day. Singtel's daily plan has unlimited data under a fair use policy. M1 sells an unlimited data roaming add-on at a flat daily fee that depends on the destination. The second is a multi-day plan, such as Singtel's 30-day ReadyRoam tiers. The third is pay per use, with no plan, billed per megabyte. Those rates add up fast, so a plan is usually the safer choice.
An eSIM data plan is normally a fixed bundle: a set amount of data for a set number of days in a set country or region. You see the full cost before you buy. There is no bill shock later, but unused data is usually lost.
A simple rule: for one or two days abroad, a daily roaming pass is often easiest. For a week or more, a fixed local or regional bundle often costs less per day. Run the numbers for your own trip.
Speed and coverage
Roaming speed depends on the partner network your phone joins. Singtel notes that its plans apply only on preferred partner networks, so you may need to pick the network by hand. If your phone joins a different network, usage can be billed at pay per use rates.
An eSIM plan connects to the network named in the plan. The speed depends on that network and the plan terms. Some plans slow down after a daily limit, and so do some roaming passes. Singtel says that after its daily fair use limit, speed is cut. Browsing and social apps still work, but streaming and large downloads may be hard.
Before a big meeting day, test your connection the night before. Do not wait until you are in the taxi.
Your phone number
This is where the two options differ most. With roaming, you keep your normal number. Roaming is an add-on to your existing line, so you keep your number and do not change SIMs. Clients can call you as usual.
A travel eSIM is usually a data plan, so it may come without a local phone number. That is fine if your team uses messaging and video apps. It is less fine if clients, banks or booking sites send codes to your home number by text.
The fix is to run both. Keep your home SIM active for calls and text codes, and switch mobile data to the eSIM. Phones that support a physical SIM plus an eSIM at the same time make this easy. Before you leave, make sure data roaming is off on the home SIM so it does not use data by mistake. Singtel warns that roaming is charged per SIM, so each device with roaming on can run up its own charges.
Phone compatibility and set up
Not every phone supports eSIM. Apple says eSIM works on iPhone XS, iPhone XS Max, iPhone XR and later models, and that you can pair a physical SIM with an eSIM. Many Android phones support it too, but check your exact model. Your phone also needs to be unlocked from a single operator before it will accept a plan from another one.
Set up usually takes a few minutes. Buy the plan, scan the QR code or follow the in-app steps, and turn the line on. Do it on home Wi-Fi before you travel, because you need an internet connection to download the profile.
Roaming set up is simple too. Operators such as Singtel and M1 let you buy a pass in their apps. Singtel says you can buy a plan up to 30 days ahead, or set its auto options to buy one for you when you land. M1 lets you switch on its unlimited data roaming add-on in its app, and its network lock keeps you on preferred partner networks.
How to choose
Use this short checklist for your next trip.
- Trip of one to three days, and you need calls on your normal number: roaming pass.
- Trip of a week or more, or several countries: compare a regional eSIM bundle with a multi-day roaming plan.
- Heavy data use, such as video calls and large files: check the daily limit on either option first.
- Codes sent by text to your home number: keep your home SIM active.
- Older or locked phone: roaming may be your only option.
Whichever you pick, set it up before departure, turn off auto options you do not want, and keep a note of the operator's support number. Limits, country lists and prices can change, so read the operator's own page on the day you buy.