D-Link DPH-150S User Manual page 82

NOTE:
If only one line in talking, once you press [Flash] function key, due to the other line is free, so you will hear the dial tone. It can build the second line through
dial, then press [Flash] function key to switch.
7.1.2. Transfer
This phone support two kinds transfer function: attended transfer and unattended transfer.
● Attended Transfer - You control the transfer. Press Transfer to put the caller on hold and dial the party to which you want to transfer the call. Either announce
the transfer or hang up after pressing the Transfer button again. That's means when transferring a call, you can optionally announce the call to the transfer recipient.
● Unattended Transfer - The SIP telephone controls the transfer after you dial the number to which you want to transfer the call. Press the number of the third
party ended with the "transfer" key to which you want to transfer the call and hang up or go on-hook. The transfer automatically occurs without speaking to the
receiving party.
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