It is defining the phone number of the operator - a convenient way to see the region from which you called and what the operator.
Due to the enforcement of Apples policy regarding blocking ads across the device, Adguard Pro had to abandon the System-wide ad blocking. It still serves as a Safari content blocker and offers custom DNS settings as a Pro package, with plans to expand. For more than 6 years Adguard helps all its users enjoy the Internet the way it should be - safe and clean.