I just purchased a 2820Vn router and was going through forums to sort out some configuration customization and realized that Draytek have a new model the IP-PBX 2820 available or in the pipeline , the question :

:?: Is the IP-PBX version of the 2820 different hardware wise ( besides the ISDN ) port from a 2820 ?
:?: If not would it be possible to upgrade to a IP-PBX firmware to enable some advanced PBX features* :arrow: ?

:arrow: * Features I am looking for are like call transfer from PSTN to a SIP trunk or call routing . ( From what I have derived this is not possible at present with the 2820Vn router - please correct me if I err ...)

Yes, very different hardware; needs more inside to do all the PBX stuff and on-board memory to store voice menus, answerphone messages etc. It also has ISDN (that's not so useful in the UK though).