Every device on a network needs a unique address to send and receive data, and the Internet Protocol provides exactly that. IPv4 uses 32-bit addresses written as four decimal octets like 192.168.1.1, giving roughly 4.3 billion possible combinations. Because that supply is nearly exhausted, IPv6 was created with 128-bit addresses written in hexadecimal groups such as 2001:0db8::1, offering a virtually unlimited pool. In mobile networks, your phone receives an IP address when it establishes a PDU session, assigned by the Session Management Function and delivered through the User Plane Function.