I would like to ask, how did Unicom's card find out how many short messages were used?

The SMS sent in Unicom card can only be viewed in the transceiver box in the mobile phone, and Unicom has no right to inquire about the detailed sending content. The detailed list of SMS and MMS includes the usage records of peer-to-peer SMS and MMS sent by mobile phones (including the other party's number, sending time and cost, etc.). ), including domestic SMS, international SMS, international roaming SMS (sending and receiving SMS when roaming abroad), international roaming MMS (sending and receiving MMS when roaming abroad) and group SMS. The specific content can only be viewed by mobile phone, not by detailed list.