Cellular Network Infrastructure » osmo-ePDG - VoWifi Evolved Packet Data Gateway

When a phone connects and the sim sequence numbers are out of sync, the authentication will fail
and the phone will additional supply Rand and Auts in the failure message.
Similar to the 3gpp rat.
The sgsn already has a test for this TC_attach_usim_resync.

To reproduce it with a real phone, you could decrease the sequence number in the hss. (AFAIR it is a sliding window, reducing the sequence number by 1 might not be enough).

UE - strongswan

   <- Auth req
   -> Auth failure (reason resync, auts, rand)
 (HLR will update the sequence numbers)
   <- Auth req
   -> Auth succeed.