T-Mobile has begun blocking iPhone users from enabling iCloud Private Relay in the US, a feature that provides an additional layer of privacy by hiding users' IP addresses and internet activity. This move follows similar actions by some European carriers, who have expressed concerns that Private Relay could impact their ability to manage telecommunication networks. T-Mobile claims that only customers with content filtering enabled, such as parent controls, are affected, but some users have reported being blocked despite not having such features enabled. The blockage can be circumvented by using a custom DNS server or a VPN, but this is not a straightforward process for most users.