How to stop transferring calls on hold

[EcoEco]

Calls on-hold are being transferred, I would like to stop on-hold calls being transferred.
We have t46U on 3CX
Currently, when the user puts a call on hold, dials another extension and chat, at the end of the chat, the call is most often transferred to the other extension (I think depending on who hangs up first). Our users specifically want to keep the call while on hold, until they choose to hit the transfer button and dial the extension. They don't like the Shared Parking option.