Comprehensive technical knowledge base covering 12 GSMA eSIM specifications. 84+ articles on Remote SIM Provisioning — SGP.02, SGP.22, SGP.32, SGP.41, SGP.29, SGP.23, SGP.25, SGP.26 and more.
Your grandparent has an old flip phone. You have the newest smartphone with every feature imaginable. You want to call your grandparent. Does your phone say: “Sorry, this person uses old technology, I refuse to connect!” No! Phones are designed to work together: your fancy smartphone still knows how to make a simple voice call that your grandparent’s flip phone can handle.
The eSIM world has the same challenge. There are billions of older eSIM chips out there running v2.x magic. When SGP.22 v3.x came along with all its shiny new spells, it had to make sure it could still talk to all those older devices: and that older devices wouldn’t get confused by the new magic.
Not everyone upgrades at the same time:
v3.x was designed for all four scenarios from day one.
Remember the handshake from the Feature Support article? Here’s the key insight for version interop:
When the Key Maker doesn’t include rspCapability, it means “I’m pre-v3.”
That’s it! That one simple rule makes everything work:
| Scenario | What Happens |
|---|---|
| New Phone + Old Key Maker | Key Maker sends no rspCapability. Phone says “Ah, old magic!” and uses only v2.x spells. |
| Old Phone + New Key Maker | Phone sends no EuiccRspCapability. Key Maker says “Old chip!” and uses v2.x profile packages. |
| New Phone + New Key Maker | Both share capabilities. Full v3.x magic unlocked! |
Different helpers use different signals to figure out what version they’re dealing with:
| Conversation | Negotiation Signal |
|---|---|
| Phone ↔ Key Maker | rspCapability fields during the handshake |
| Key Maker ↔ Key Maker (server to server) | X-Admin-Protocol HTTP header (same as v2.x) |
| Phone ↔ Magic Vault Chip | The Phone’s Assistant asks the chip for its highestSvn |
| Human-Readable Website (HRI) | Different URL versions: no negotiation needed! |
When the Key Maker is about to send a secret key to a phone, it checks what versions the chip supports:
It’s like a translator who can speak both ancient and modern languages: always choosing the one the listener understands best.
The v3.x rulebook says every server must follow these politeness rules:
rspCapability in their responsesThis backwards-compatibility design means you could take a brand-new v3.1 phone to a mobile company running a 5-year-old v2.x Key Maker: and everything would work perfectly. The phone simply becomes a well-behaved v2.x phone for that conversation. It’s like being fluent in both modern slang and old-fashioned language, switching effortlessly depending on who you’re talking to!
Kid-friendly version of Version Interoperability