In our CEO's office, we installed a conference phone. I would like his ext to ring both his normal phone, and the conference phone so that he can answer on either device. We also have several users that want to run am iPhone SIP app for when they are mobile in the company. Again here it would be nice to ring both phones if registered, and allow answering on either phone. Can multiple phones share the same extension? I know I can do it via a ring group, but depending on the number of users, that could get messy really quick.