All non-null parameters in the query string must be serialized as a JSON string with keys sorted in lexicographic order, to be used as the signature input.
3.
The signature content (signContent) must be encrypted using the MD5 algorithm (default: 32-character lowercase alphanumeric string).
4.
group_id must be a valid and existing SIM-plan group identifier.
5.
The customer associated with the group ID must match the customer identity of the current API request.
This is a synchronous interface — the complete query result is returned immediately upon request.
2.
If sim_id is not provided, the full list of ICCIDs in the group will be returned.
3.
The returned SIM card count is based on per-operation counting — each add operation is counted individually without deduplication. Note that duplicate additions may cause the count to exceed expected limits.