Over WANs (Wide Area Networks), up to 100 milliseconds is typical.  It depends on how far away the public time server is, or more specifically, how many hops between you and the server.  Within a LAN (Local Area Network) using a dedicated NTP Time Server, 0.5 to 2 milliseconds is typical.  The internal accuracy of the CDMA Network Time Server is on the order of 10 microseconds.  It can easily keep all clients on a LAN synchronized to typically within 0.5 to 2 milliseconds.