VoIP call transfers: blind, attended, and consultative transfer

A blind transfer sends the caller to a destination without first speaking to the recipient. An attended transfer lets the operator consult the recipient before connecting the caller. Different PBXs implement these actions using REFER, re-INVITE, bridging, or vendor-specific logic.

Troubleshooting checklist

• Confirm the user has transfer permission.
• Check whether the destination is internal, external, or restricted.
• Follow the original dialog and the new call leg separately.
• Verify the transfer target is formatted correctly.
• Test what happens when the recipient is busy, unanswered, or rejects the call.
• Check recording, caller ID, and queue behaviour after the transfer.

Related: SIP methods, SIP headers, and dial plans.