What is "SIP forking"?

SIP forking is defined as the process where a single INVITE request is sent to multiple user endpoints. This technique allows multiple devices, which may be registered to the same SIP account, to receive a call simultaneously. The first device that responds typically establishes the call, while the other devices will still be waiting for acknowledgment. This capability enhances flexibility and ensures that calls can reach users regardless of which device they choose to answer on.

For instance, if a user has both a desk phone and a mobile device registered under the same SIP account, forking allows the incoming call to ring on both devices at the same time. This is particularly useful in scenarios where users may not be at their primary device, providing them the opportunity to answer the call on another available device.

The other options do not accurately describe SIP forking. Terminating call sessions, redistributing network resources, or simultaneous transcription of SIP messages do not relate to the concept of forking in the context of SIP communications. Therefore, the emphasis on sending a single INVITE to multiple endpoints captures the essence of what SIP forking entails.