When the Nokia corporation had an accreditation level of joyn, what was the accreditation type?
CREATE TABLE "ecosystem_operators_mobile_phone_and_cli" (
  "company_name" text,
  "hardware_model" text,
  "accreditation_type" text,
  "accreditation_level" text,
  "date" text
);
SELECT "accreditation_type" FROM "ecosystem_operators_mobile_phone_and_cli" WHERE "accreditation_level"='joyn' AND "company_name"='nokia corporation';