The QR code you scan to install an eSIM is not the eSIM. It is an address and a ticket. Understanding that makes every activation problem easier to fix.
What is in the QR code
Decode one and you get a short string like LPA:1$smdp.example.com$ABCD-1234-EFGH. Three parts: LPA:1 says it is an eSIM activation string; the middle part is the SM-DP+ address, the server that holds your profile; the last part is the activation code, a one-time ticket that tells that server which profile to release. Your phone's eSIM software (the LPA, local profile assistant) contacts the server, presents the ticket, and downloads the carrier profile into the phone's secure chip. That download is the actual eSIM.
This is why every eSIM can also be installed by typing the SM-DP+ address and the activation code manually: the QR code is only a convenient way to carry that string. It is also why a QR code is single-use in practice; once the profile is downloaded, the ticket is spent.
Installation vs activation
Installing puts the profile on the phone. Activating starts the plan's clock. Plans differ here and it matters: some start counting validity the moment you install, others on first use of data. The plan page and your PDF say which. If a plan activates on installation, install it the day you travel, not the week before.
Why installs fail, in order of likelihood
- No internet during install. The phone has to reach the SM-DP+ server. Be on Wi-Fi or another SIM's data when you scan.
- Carrier-locked phone. A phone locked to a carrier will refuse foreign profiles. Check in settings; the lock has to be removed by the original carrier.
- Scanning from the same phone. You cannot scan a QR code displayed on the phone you are installing to. Use the manual codes, the direct install link on the delivery page, or show the QR on another screen.
- Already used. If the profile was downloaded once (even to a phone you later reset), the code is spent. A factory reset deletes eSIMs; back that in mind before wiping a phone.
- Region-limited phone. Phones sold in mainland China generally have eSIM disabled. Some carrier-branded models elsewhere too.
After it installs and does not connect
Turn on data roaming for the eSIM line; travel eSIMs are roaming profiles and many phones default roaming off. Make sure the eSIM is selected for mobile data, not your home SIM. If the plan needs a specific APN it is on your PDF; most set it automatically. Give it a minute after landing; the network registration can lag.
The PDF
On SimBear every eSIM comes with a PDF holding the QR code, the SM-DP+ address, the activation code, the full LPA string, the plan's activation policy and your anonymous login key. If the phone changes or the tab closes, the PDF is the copy that matters. Keep it.