Is it possible to transfer a call when the phone has no specific Transfer button? Is it possible to set up some other button or sequence that will provide the means to effect the transfer?

You've not stated what product you're talking about? Is this a phone ? An app ? Software ?

Well, it's in the IPPBX section and I thought my question was clear that I'm looking for an IPPBX function.

However, you're right, I should have stated that I am referring to the 2820 IPPBX.

I realise there may be no such transfer code, but I thought it possible that there is. So ANY phone can make a transfer, even if it has no specific transfer button.

On older PBXs you had a choice of LD and ER but IP PBXs recognise neither as they are in-band analogue signalling systems. On an FXS phone port, some will recognise LD break... I'm not sure if the Vigor will, but probably not... I'd ask support. Is this an analogue phone you're using?

There's one analogue and several softphones.

I could buy a different softphone with transfer capability, but trying to first determine if there's any way to avoid that and use the one I already have.

I'd expect most analogue phones to have a recall button, but I can't remember if the PBX2820
supports that...and the softphones would normally have the function...so I really can't be much help