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.
You’re at a magic convention. You meet another magician and want to perform a trick together. But before you start pulling rabbits out of hats, you need to know: does this magician know the levitation spell? Can they do the disappearing coin? Is their spellbook the old edition or the new one?
If you try a spell they don’t know, the trick fails: maybe even disastrously! So before any magic happens, you do a quick check-in: “Here’s what I can do. What can you do?”
That’s exactly what the Feature Support system does in SGP.22 v3.x: it’s the friendly handshake where everyone shares their magical abilities before any serious spells get cast.
Not every phone, chip, or server runs the same version of the eSIM rulebook:
Without a handshake, the Key Maker might try sending a “Remote Control spell” to a phone that has no idea what that means: and everything breaks!
During the very first secure connection (called Common Mutual Authentication), everyone exchanges a little card with their capabilities:
| Who? | What They Share | What It Says |
|---|---|---|
| The Magic Vault Chip | EuiccRspCapability |
“I can do RPM, MEP, Push… here’s what I support” |
| The Phone’s Assistant | lpaRspCapability |
“I’m running version X.Y and I can do these tricks” |
| The Key Maker / Post Office | rspCapability |
“I’m running version X.Y, and I support these features” |
If the Key Maker’s card is missing a certain trick (or missing rspCapability entirely), everyone knows to stick to the simpler, older spells.
Inside the spellbook, every magical instruction has tiny hidden tags that say when it can be used:
| Tag | Meaning (In Plain English) |
|---|---|
#SupportedFromV3.0# |
“Only use this spell if everyone involved is v3.0 or newer” |
#SupportedForRpmV3.0# |
“This is a Remote Control spell: only works with RPM-capable chips” |
#SupportedForMEPV3.1# |
“This is a Two-Cloaks trick: only for MEP-capable phones” |
#SupportedForPushServiceV3.1# |
“This is a Doorbell spell: only for Push-capable phones” |
#MandatoryFromV3.1# |
“This used to be optional, but from v3.1 onwards it’s always required” |
The Key Maker reads these tags and only includes spells that both sides understand.
Golden rule: If the Key Maker or Post Office doesn’t include rspCapability in their response, it means they’re running a pre-v3 version. The Phone’s Assistant immediately switches to “old magic only” mode: no Remote Control, no Doorbell, no Two Cloaks.
This is the genius of the system: it gracefully falls back to whatever works. No errors, no crashes, no failed tricks.
The Key Maker receives EuiccRspCapability from your phone:
The Key Maker thinks: “OK, I can send Remote Control spells, but I won’t try Device Change or Push: they wouldn’t understand!”
Without this handshake system, every time a new spell was invented, all the old phones and servers would need updates just to not crash when they saw an unfamiliar instruction. The Feature Support system means old and new can work together forever: like a magician who knows which tricks to keep in the pocket!
Kid-friendly version of Feature Support