In a GPRS system, a method of a mobile station acquiring an IP network address. The method comprises the steps of:the mobile station generating a link identifier and sending it to a gateway over a wireless link in a network address request together with a request to check if the link identifier is unique;the gateway receiving the network address request and checking if the link identifier is unique;the gateway responding with a network address request response including either the sending a unique link identifier confirmed as being unique or a different unique link identifier;the gateway sending a network prefix to the mobile station;the mobile station combining the interface identifier and the network prefix to generate the IP network address.