Call of Duty: Modern Warfare II will require players to register with a phone number on Battle.net to play the game, in order to make players responsible for their actions. The game is set for release later this month on October 28th.

The phone verification system, which Activision Blizzard calls SMS Protect, is meant to cut down on toxic behavior from players, preventing them from creating endless new accounts to evade bans or to cheat. “Limiting the number of free accounts that a single person can create helps keep players accountable for their actions and, in turn, reduces toxicity and cheating and ensures a positive community experience for all players,” Activision Blizzard’s support page reads.

The problem is that SMS Protect is designed for text-enabled mobile phones, and doesn’t treat all phone numbers equally. A separate Battle.net support page notes that “mobile phones with prepaid plans may not work with the phone notification service.” It also doesn’t work with VoIP numbers. That restricts the service to players with postpaid cellular plans, which may not be affordable or easily accessible to many players around the world.

one Modern Warfare II beta player told PCGamer last month that they were asked for a “postpaid phone number” to start the game, with Battle.net refusing to accept the number associated with their prepaid Cricket Wireless plan. “This seems very wrong to require video game players to enter into a contract with a telecom company before being allowed to play the game they paid for,” they said.

Requiring players to provide a phone number isn’t new (Dota 2 and Rainbow Six Siege both require them for ranked play) but there haven’t been widespread reports of problems with prepaid phone plans with these previous implementations. One player we spoke to was blocked from playing Overwatch 2 when they entered the same number they’d used to successfully play Dota 2 for years.

It’s unclear whether Activision Blizzard’s phone number requirements will apply equally for Modern Warfare II players across both Battle.net and Steam, given the game is available across both PC digital stores. some commenters on Reddit report being asked for a phone number when trying to play the beta through Steam, while others said they were not. Overwatch 2 is currently only available via Battle.net.

In the case of Overwatch 2Activision Blizzard has said that it’s relaxing its SMS Protect requirements for anyone who played the original Overwatch and has a connected Battle.net account. It’s unclear if there’ll be similar allowances made for Call of Duty: Modern Warfare II players. A spokesperson for the company did not immediately respond to The Verge‘s request for comments.