Telstra International Roaming vs Local eSIM: Save Money

Telstra international roaming typically costs $10 per day for a small data allowance, which quickly adds up over a multi-week trip through Southeast Asia. By switching to a local travel eSIM, you can access significantly higher data limits at a fraction of the cost while maintaining a faster, local connection.

The Reality of Telstra International Roaming

For many Australian travelers, the Telstra International Day Pass is the default choice. It offers the convenience of keeping your home number active without the need to swap physical SIM cards. However, this convenience comes at a steep price. If you are backpacking through Thailand (dest:th) or exploring several countries in (dest:as-20), that $10 daily fee can easily exceed $300 for a month-long trip.

Beyond the cost, there is the issue of performance. When you roam with a home carrier, your data is often routed from the local cell tower in Bangkok or Hanoi all the way back to Australia before it reaches the open internet. This process, known as backhauling, significantly increases latency. This means that even if your phone shows a 5G signal, your maps might lag, and your social media feeds may take forever to refresh.

The Local eSIM Alternative

An eSIM is a digital version of the traditional SIM card. Instead of fumbling with a metal tool at the airport, you simply scan a QR code to download a cellular profile to your phone. Services like Thai Simcard provide these digital profiles, allowing you to connect directly to local networks like AIS, DTAC, or Viettel the moment you land.

Data Only Plans and Local Numbers

Most travel eSIMs are provided as "data only" plans, which have no local number. For the modern traveler, this is rarely a dealbreaker. Apps like WhatsApp, Messenger, and Telegram use data to make calls and send messages, so your contacts won't notice a difference. Furthermore, apps like Grab and Foodpanda allow you to register with your Australian number or an email address, meaning you can still hail a ride or order a late-night pad thai without needing a Thai phone number.

Comparison: Telstra vs. Optus vs. Travel eSIM

Feature	Telstra Day Pass	Optus Roaming	Travel eSIM (Thai Simcard)
Daily Cost	~$10 AUD	~$5 AUD	Fraction of daily roaming
Data Limit	Often capped at 1GB/day	Fixed total (e.g., 5GB)	High or Unlimited options
Network Speed	Throttled after cap	Varies	Local 4G/5G speeds
Setup	Automatic	Automatic	QR Code Scan
Convenience	High	High	Moderate (Initial setup)

Coverage Realities: From Bangkok to the Ha Giang Loop

When you rely on Telstra international roaming, your phone will connect to whichever local carrier has the cheapest wholesale agreement with Telstra. This isn't always the carrier with the best towers in the area you are visiting.

Thailand (dest:th)

In Thailand, the big three are AIS, DTAC, and TrueMove. AIS is widely considered the gold standard for coverage, especially if you are heading to remote islands or the mountainous regions of the north. If you are using a local eSIM, you are tapping directly into these robust infrastructures. This is essential for navigating busy street food markets or checking into your hostel in a remote village.

Vietnam

Vietnam has some of the best mobile connectivity in the region, but coverage varies by province. If you are following our Ha Giang Loop Guide: Everything You Need to Know, you will need a provider that covers the northern highlands. Viettel is the dominant player there. Relying on a roaming plan that might default to a smaller carrier could leave you without a signal exactly when you need to check your GPS on a mountain pass.

Cambodia and Beyond

In Cambodia, carriers like Cellcard and Smart offer excellent coverage in Phnom Penh and Siem Reap. However, if you are heading to the islands like Koh Rong, a local connection is much more reliable than a roaming signal that has to bounce back to an Australian server.

How to Install Your Travel eSIM

Before you purchase, you must ensure your phone is unlocked and supports eSIM technology. You can check the list of compatible devices to be sure.

For iPhone Users

1. Go to Settings > Cellular (or Mobile Data).
2. Tap Add eSIM.
3. Choose Use QR Code and scan the code sent to your email by Thai Simcard.
4. Label your new plan as "Travel" and your Telstra plan as "Home."
5. Set the Travel plan as your Cellular Data line.

Pro Tip: Turn off "Data Roaming" on your Telstra/Home line to avoid accidental charges, but keep the line "On" if you need to receive SMS for bank 2FA codes.

For Android Users

1. Go to Settings > Connections > SIM card manager.
2. Select Add mobile plan.
3. Scan the QR code provided.
4. Once the profile is downloaded, ensure the eSIM is toggled on and selected as the primary source for mobile data.

For a more in-depth walkthrough, refer to our setup instructions.

Data Needs by Activity

Understanding how much data you will use helps you choose the right plan.

• Navigation: Google Maps uses about 5MB per hour of active navigation. It is a good idea to download offline maps while on Wi-Fi to save data.
• Social Media: This is the biggest data drain. Uploading a video to TikTok or Instagram can use 50-100MB in seconds.
• Ride-Hailing: Using Grab to get around cities like Saigon—perhaps while following our 3 Days in Ho Chi Minh City: The Perfect Itinerary—uses very little data, but the connection must be stable so the driver can find you.
• Streaming: Watching YouTube or Netflix in HD will burn through 1GB-3GB per hour. Save the binging for the hostel Wi-Fi.

Why Buy Before You Fly?

While you can buy SIM cards at airport kiosks, they are often more expensive and come with long wait times. After a long flight from Sydney or Melbourne, the last thing you want to do is stand in a queue at 2 AM. By getting your eSIM from Thai Simcard before you leave Australia, you can activate it while the plane is taxiing to the gate. You’ll have a working connection to message your family or book a ride before you even step off the aircraft.

Managing Two SIMs Simultaneously

The beauty of eSIM technology is that it allows for Dual SIM functionality. You don't have to choose between your Australian number and a local data plan; you can have both. This is particularly useful for receiving those essential one-time passwords (OTP) from your bank or airline. As long as you have "Data Roaming" turned off for your Telstra line, you can usually receive incoming SMS for free (check your specific Telstra plan for details), while your travel eSIM handles all the heavy lifting for internet usage.

The bottom line

Telstra international roaming is a convenient but expensive luxury that often provides subpar data speeds due to latency. For backpackers and travelers looking to maximize their budget, a local travel eSIM is the superior choice. It offers local network priority, significantly lower costs, and the flexibility to stay connected across multiple countries in Southeast Asia without the fear of a massive bill waiting for you at home.