Transferring an active phone call to another phone number

This question was asked a while back and hoping someone may have the answer. I've copied the question below. It is the exact issue I am having now while trying to work from home on my company cell. I need to be able to accept live calls but then transfer that live call off to another employee's phone number. Not conferencing, I need to be able to hang up without disconnecting the call. Thank you all for any suggestions.

***Does anyone know how to transfer an active / live call that you are currently engaged in to another number? This is not call forwarding. I called my cell network provider (ATT) and there is no such way on their end. Does anyone know of an app that can do this?

I am trying to work from home, but if I get a call on my cell that needs to be routed to another department, I don't want to tell the customer to hang up and dial X-number. I think it is much more professional to transfer the call.

Call conferencing won't work either unless I decide to stay on the line the whole time (the call would disconnect as soon as I hung up).