How to change Unicom's secondary card into the main card?

If the secondary card of Unicom needs to be replaced by the primary card, the owner can bring his valid ID card to the main hall of Unicom where the number belongs, and replace the secondary card with the primary card, which is subject to the actual operation of the business hall. Please consult Unicom customer service for the address, certificates and precautions of the business hall.

Tips: Take Jiangsu Province as an example. There may be differences in policies among provinces and cities, and the attribution policy shall prevail.