In order to prevent some users from maliciously harassing others using Internet phone, some Internet phone systems have set up rules to restrict calls: if a user repeatedly calls one or more numbers using direct dial within a short period of time, the user's account will be frozen for a period of time (10 minutes to 24 hours), and direct dial calls cannot be made during the freezing period; if the violation is repeated multiple times within a day, the freezing period will be extended (if it is more than 3 times, it will be frozen for 24 hours).