Can I transfer a call to another number mid-call (on my iPhone)?

I would like to transfer a call (mid-call) to another number. Is it possible?

What you can do is add another number to the call once you’ve started it, then you can talk using the other phone number that you added.

The only thing is you cannot hang up on he original number once you add the second number or else both numbers will be disconnected.

I do this all the time by pushing ## ...it tells me I am transferring the number and then I put in the number to route to... only, it has do be done within 20 seconds or you have to start over and push ## again

The final step is done by the phone... you wait until it disconnects you

This works on my iPhone X with ATT family plan