Method of protecting an identity of a mobile station in a communications network

1. A method of hiding an identity of a mobile station in a communications network having an access node and a gateway node, the method comprising receiving a first mobile station identifier value at the access node, storing the first value in the access node, receiving a second mobile station identifier value, correlating the second identifier value with the first identifier value in the access node, sending the first and second identifier values from the access node to the gateway node over an interface, storing the first identifier value and the second identifier value in the gateway node, and correlating the second identifier value with the first identifier value in the gateway node, wherein the access node correlates the first identifier value and the second identifier value with a context identifier value.

2. The method according to claim 1 , wherein the access node stores the context identifier value in the access node, sends the context identifier value to the gateway node over an interface, and wherein the gateway node stores the context identifier, correlating the first and the second identifier with the context identifier.

3. The method according to claim 2 , wherein the access node uses the context identifier value to identify the correct mobile station context information for the mobile station identified by the first and the second identifier in messages sent to and received from the gateway node.

4. The method according to claim 3 , wherein the gateway node uses the context identifier value to identify the correct mobile station context information for the mobile station identified by the first and the second identifier in messages sent to and received from the access node.

5. The method according to claim 1 , wherein the context identifier value is derived from the first or the second identifier value.

6. The method according to claim 5 where the derivation step is based on a cryptographic hash function that generates a hash value which is used as input to the context identifier value.

7. The method according to claim 1 , wherein the first identifier value and the second identifier value are sent from the access node to the gateway node in the content field of messages exchanged between the access node and the gateway node.

8. The method according to claim 1 , wherein the first mobile station identifier value, the second mobile station identifier value, and the context identifier value, are stored in mobile station context information in the access node and the gateway node.

9. The method according to claim 8 , further comprising verifying that the mobile station sending the first identifier value is the same as the mobile station sending the second identifier value.

10. The method according to claim 9 , wherein the step of verifying takes place in the gateway node.

11. The method according to claim 9 , wherein the step of verifying takes place in an AAA server node.

12. A communications network, comprising an access node via which a mobile station can access the network and a gateway node, wherein the access node is configured to receive a first mobile station identifier value from a mobile station wishing to connect with the network, to store the first identifier value, to receive a second mobile station identifier value, to correlate the second identifier value with the first identifier value with a context identifier value, and to send the first and second identifier values to the gateway node over an interface, and wherein the gateway node is configured to store the first identifier value and the second temporary identifier value, and to correlate the second identifier value with the first identifier value.

13. A method of hiding an identity of a mobile station in a communications network having an access node and a gateway node, the method comprising receiving a first mobile station identifier value at the access node, storing the first value in the access node, receiving a second mobile station identifier value, correlating the second identifier value with the first identifier value in the access node, sending the first and second identifier values from the access node to the gateway node over an interface, storing the first identifier value and the second identifier value in the gateway node, and correlating the second identifier value with the first identifier value in the gateway node, wherein the access node correlates the first identifier value and the second identifier value with a context identifier value and uses the context identifier value to identify the correct mobile station context information for the mobile station identified by the first and the second identifier in messages sent to and received from the access node.

14. The method of claim 1 , wherein the identity of the mobile station is a MAC address of the mobile station.