Question: In a Bearer-Independent CS Core Network, if a (G)MSC server indicates support for fast tunnelling during the Prepare Bearer procedure, what are the permissible tunnelling methods the Media Gateway (MGW) can select from?
Option 1: Fast Tunnelling or Non-Tunnelling method
Option 2: Delayed Tunnelling or Fast Tunnelling
Option 3: Only Fast Tunnelling, with no alternative options
Option 4: Any of Fast Tunnelling, Delayed Tunnelling, or Non-Tunnelling methods
Explanation: According to the tunnel selection process in a Bearer-Independent CS Core Network, if the (G)MSC server indicates support for fast tunnelling, the MGW is specifically allowed to choose between utilizing fast tunnelling or opting for the non-tunnelling method. This ensures flexibility in handling the bearer establishment based on network conditions and requirements.