VoIP numbers cannot be used for two reasons. First, if say a user’s account was successfully hacked, the hacker could use a burner number to secure it and prevent it from being accessed by the original poster again. Secondly, leaderboard protocols like Overwatch PC top 500 is intended to keep individuals in that leaderboard. If SMS protect allowed VoIP numbers, then the whole purpose of using SMS Protect for the Top 500 would be defeated.