Malaysia is divided into two completely different halves. On the peninsula are Kuala Lumpur, Penang, and Langkawi; Kota Kinabalu and the rest of Sabah are separated from them across the South China Sea on the island of Borneo, a quick flight away instead of an easy taxi ride.
If the trip includes both Kuala Lumpur and Sabah, there’s no need to sort out a new SIM after the flight. The same eSIM can stay on the phone throughout the trip. A traveler can land in Kuala Lumpur, use it there, and still have data when they reach a lodge near Kota Kinabalu.
Further Reading: The Sabah, Borneo and Kota Kinabalu Travel Guide
Set up the eSIM before you ever board a flight
The eSIM installs automatically at home over Wi-Fi days before leaving, little is left to work out at arrivals. The plan itself hadn't even begun by then, because its days only start ticking from the first connection made within Malaysia.
For the first connection, it has a 180-day window from the date of purchase, so that covers even a trip that is booked well in advance and paid for well in advance. Once you land, all that you have left to do is select the eSIM for mobile data and enable its data roaming.
The second SIM is a regular SIM that remains in the phone the entire time, untouched. Disabling its own data roaming before leaving is also a good idea, to make sure a new network doesn't start charging in the background as soon as the eSIM kicks in for data.
The same two networks follow you to Sabah and Sarawak
All Travelsim Asia Malaysia plans switch to the two biggest mobile providers in Malaysia, Maxis and CelcomDigi, with 5G available on supported handsets. On a route spanning both sides of the South China Sea, that pairing is more crucial than on a city break within the peninsula.
Opensignal gave CelcomDigi a score of 8.8 out of 10 for coverage in populated areas in its July 2026 report, based on data collected from April to June. Maxis scored 7.0. An eSIM with access to both networks gives travelers another option when they are moving between different parts of Malaysia.
The plan is valid across all of Malaysia, including, as you'd expect, Sabah and Sarawak, so that eSIM you bought in Kuala Lumpur keeps working after the brief air journey to Kota Kinabalu, no second purchase required. Away Lands has a guide to Sabah, Borneo and Kota Kinabalu for planning that leg of the trip.
Even with both networks in tow, the depth of the rainforest and the crossings out to offshore islands can lie beyond any local signal, every bit as much a limitation of a travel eSIM as of a Malaysian SIM card that you buy on the ground. We recommend taking the extra minute to save a route along with the pickup before you head out there.
Further Reading: Grand Hyatt Kuala Lumpur Review: Luxury Hotel in Malaysia
Choosing how much data actually makes sense
This eSIM is data-only, meaning that there is no Malaysian phone number, no standard calls or texts. It allows a traveler to keep their normal number and messaging apps running just like before, while also being able to share the connection via hotspot to a laptop or travel partner.
You don't need to add anything new to avoid running out during the trip. You can also add more data from the dashboard in the original confirmation email directly to the same eSIM already on the phone.
As of this writing, 5GB over 30 days runs $7.99, enough for maps, ride-hailing, and messaging when traveling across both halves of a trip like this one. That option sits alongside smaller and larger plans on the same product page, which can better match the trip length than a guess.
Get your eSIM here before the flight out, and it is already running and connected by the time Kota Kinabalu comes around on the second half of the trip.
