Question: What happens when the INTERROGATION timer set by the Gateway Mobile Location Centre (GMLC) expires before receiving an interrogation response from the Home Location Register/Home Subscriber Server (HLR/HSS)?
Option 1: The GMLC sends a repeat interrogation request to the HLR/HSS.
Option 2: The GMLC indicates a location failure to the Location Services (LCS) client and transitions back to the NULL state.
Option 3: The GMLC switches to an alternate HLR/HSS for the interrogation response.
Option 4: The GMLC extends the timer for a predefined additional duration.
Explanation: This is correct because, according to the described functionality, if the INTERROGATION timer expires before the GMLC receives an expected response from the HLR/HSS, it triggers two specific actions: (1) it notifies the LCS client of a location failure, indicating the process did not complete successfully, and (2) it reverts to the NULL state, resetting its operational mode in anticipation of new requests or operations. This behavior ensures timely handling of location service requests and efficient resource management within the telecom network.