The service of "Travel Card" uses the data of the base station where the user is located. When querying data, it sends a query request to the base station, which receives it and feeds it back to the headquarters to form a record, and finally sends it back to the owner.

In order to ensure continuous communication and achieve no blind area coverage, the signals of base stations in the two places at the junction of administrative divisions may cross-cover, resulting in deviation of results. It is also possible that you haven't visited the service base station for a long time, and the base station hasn't received your information request, which makes it impossible for the base station to export your itinerary data at the first time, and thus makes it impossible to query your data on the mobile phone.