Question: In an IP Multimedia Subsystem (IMS), what is the primary difference between a Blind Transfer and an Assured Transfer when transitioning a session from the Initiator (I) to the Target (T) via the Recipient (R)?
Option 1: The direction of the Refer message, which in Assured Transfer is sent from R to I, and in Blind Transfer from I to R.
Option 2: The timing of the BYE message sent by the Initiator (I) to terminate its connection with the Recipient (R), relative to the completion of the Refer message.
Option 3: The type of session (e.g., voice, video) that can be transferred in each scenario, with Assured Transfer limited to voice.
Option 4: The requirement for the Target (T) to acknowledge the transfer before it is considered successful, applicable only to Blind Transfers.
Explanation: The key distinction between a Blind Transfer and an Assured Transfer lies in the timing of when the Initiator (I) sends the BYE message to terminate its session with the Recipient (R). In a Blind Transfer, I sends the BYE message immediately after sending the Refer message to R, without waiting for confirmation that the new session between R and T is successfully established. In contrast, an Assured Transfer involves I waiting for the Refer operation to complete successfully before issuing the BYE message, ensuring that if the new session fails, the original session between I and R remains intact.