Question: Upon receiving an OPEN CHANNEL for IMS command from the UICC, what action should the Mobile Equipment (ME) take if there is no active IMS PDP/PDN context due to changed network conditions after a successful IMS registration?
Option 1: The ME shall execute the command using an alternative available channel.
Option 2: The ME shall inform the UICC using TERMINAL RESPONSE (network currently unable to process command) and the UICC shall wait until the next IMS registration event.
Option 3: The ME shall automatically establish a new IMS PDP/PDN context to fulfill the request.
Option 4: The ME shall reject the command with a permanent failure cause, requiring manual intervention.
Explanation: According to the specified behavior for handling OPEN CHANNEL for IMS commands, if the ME is unable to process the command due to the absence of an active IMS PDP/PDN context (a condition that can arise from changed network conditions after a successful IMS registration), it should inform the UICC using TERMINAL RESPONSE. Upon receiving this failure cause, the UICC waits until the next IMS registration event before sending another OPEN CHANNEL for IMS command, ensuring coordinated handling of resource availability and application requests between the ME and UICC.