Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE shop ( shop_id number, shop_name text, location text, open_date text, open_year number )
TABLE: CREATE TABLE device ( device_id number, device text, carrier text, package_version text, applications text, software_platform text )
TABLE: CREATE TABLE stock ( shop_id number, device_id number, quantity number )

### Question ###
What are the carriers of devices that are in stock in more than a single shop?

### Accurate SQL ###

SELECT T2.carrier FROM stock AS T1 JOIN device AS T2 ON T1.device_id = T2.device_id GROUP BY T1.device_id HAVING COUNT(*) > 1