SM-DP+ stands for Subscription Manager Data Preparation, and the plus marks the version used for consumer eSIMs. In plain terms it is a secure remote server that holds your eSIM profile until your phone is ready to collect it. When you buy a prepaid travel eSIM, the profile is prepared and parked on one of these servers; nothing lands on your device until you start installation.
The connection matters because a profile is not a plain file you can copy around. It carries operator credentials that have to be delivered over an encrypted channel to exactly one device, once. The SM-DP+ enforces that: it authenticates your phone, releases the profile, and then marks it as consumed so it cannot be pulled down a second time somewhere else. That one-time behaviour is why a fresh install is the norm rather than a re-download.
So what does the address in a QR code actually do? A QR code is not the profile itself. Scanning it simply tells your phone which SM-DP+ server to contact and which activation code to present, so the device knows where to knock and what to ask for. Your phone then reaches out, proves who it is, and downloads the profile directly. That is also why you need a working internet connection during setup even though the data plan itself is not live yet: the download happens over Wi-Fi or an existing line.
If installation stalls, it is usually the handshake, not the plan. Confirm you are online, check your device compatibility, and follow the step-by-step install and activate guide rather than rescanning repeatedly. Once the profile transfers, the server’s job is done and the eSIM lives on your phone.