Why do you receive a short message that 3G traffic packets are automatically upgraded to 4G traffic packets?

I received a text message saying that the 3G traffic packet was automatically upgraded to the 4G traffic packet, because the original 3G traffic packet was offline. Telecom companies upgrade 4G packets for all old users of 3G packets. For example, the original 3G traffic packet 20 yuan 150M, and the upgraded 4G traffic packet 20 yuan 300M. From next month, we will enjoy more traffic at the same price. This upgrade is free, and there will be no impact except the renaming of monthly traffic packets. For more service benefits, click on "official website" customer service 222 below to answer your questions.