Question: What is the expected response from the Mobile Station (MS) when it receives a REQUEST SECONDARY PDP CONTEXT ACTIVATION message with an unspecified cause for rejection?
Option 1: The MS sends a REQUEST SECONDARY PDP CONTEXT ACTIVATION REJECT message with cause #31 "activation rejected, unspecified".
Option 2: The MS sends a REQUEST SECONDARY PDP CONTEXT ACTIVATION ACCEPT message.
Option 3: The MS ignores the request and takes no action.
Option 4: The MS sends a REQUEST SECONDARY PDP CONTEXT ACTIVATION REJECT message with cause #26 "insufficient resources".
Explanation: According to the specification, when the MS rejects the network-requested secondary PDP context activation, it sends a REQUEST SECONDARY PDP CONTEXT ACTIVATION REJECT message with an additional cause code. If the rejection is due to an unspecified reason, the MS should use cause #31 "activation rejected, unspecified".