Travel itinerary code records the location according to everyone's mobile roaming records. The rule that a card can have roaming records in different places is to make phone calls in the same place more than twice a day, with an interval of more than four hours!
If everyone's mobile phone is dual-card, then the two cards are in different locations. For example, one card is a home card and the other card is in a different place. If people are in different places and don't use their home cards, there may be a problem that the travel code can't find the travel data.
The communication travel card is located by the mobile phone signal. The itinerary inquiry service jointly launched by China Information and Communication Research Institute, China Telecom, China Mobile and China Unicom was opened to the public on February 13, and users can inquire about their visits for free within 14 days.
The data source of location query service provided by travel card is mobile phone signaling data, which is obtained through the location of the base station where the user's mobile phone is located.