1. The recruitment information has expired or been deleted: if the recruitment information has expired or been deleted, the phone number will also disappear.
2. Website function restriction: Some recruitment websites may not provide the function of displaying telephone numbers, or the display of telephone numbers is restricted for security reasons.
3. Incomplete recruitment information: If the recruitment information is incomplete, including the phone number is not filled in or filled in incorrectly, the phone number will also be invisible.