This service allows a customer to call another party during an existing call and add this party to the call, creating a three-way conversation.
User operation
When on a call press flash-hook and then dial the third party’s number.
If the third party answers, hit flash-hook again to add both of you to the original call, connecting all three parties.
If the third party does not answer or their line is busy, hit flash-hook twice to rejoin the original call.
If you hang up you will receive a ring back reminding you that the original call is still on hold you can pick it up to resume the call.