Returns a single SIM record. The {id} path parameter accepts either:

• System ID: the platform-assigned 24-character alphanumeric identifier (e.g. 5f1b2c3d4e5f6a7b8c9d0e1f).

• ICCID: an all-digit 18–22 character Integrated Circuit Card Identifier (e.g. 8901260123456789012). The server detects an all-digit value in the 18–22 character length range as an ICCID and performs a lookup by ICCID instead of by system ID. The same company-scoped permission check applies in both cases; a SIM the caller cannot access returns 404 (not 403) to avoid leaking existence.