The latter is the communication between a GPRS MS and an ISP, for example. The GPRS system provides IP connectivity between MS and ISPs, using the GSM standard, data transfer is based on the common internet protocol (IP), which means that packet data transmission is carried out on an end-to-end basis (including the air interface). From the users point of view a modem connection to the internet is provided when using an GPRS MS.
An interface that communicates using the IP protocol must have an IP address and identifier, now since the GPRS system uses the IP protocol for both the end-user traffic and the system user traffic, both MSs and system components need IP addresses.
The IP addresses used in the GPRS system, for system and for end-user communication, can be public, dynamic or static.