This page describes how you can setup simulring for multiple phones in the context of an user. This is useful if you want to ring multiple phones or softphones when a user extension is dialed.
Go to Advanced User Mode and associate or create a new SIP/IAX channel and set the caller ID to the main extension. This way calls from any secondary channels will appear with the same caller ID as the main channel. If you want to use MWI (message waiting indicator), set the mailbox for the channel accordingly. You can only associate mailboxes and channels that haven't been associated to other users.
It makes sense to create a numbering plan which separates primary extensions from secondary ones. So for example you could dedicate all channels starting with 445XX as the primary extensions and use 446XX for secondary channels etc. Remember that ipbx will attempt to dial channels by their name/number directly even if they are not associated to a specific user.
Users with multiple associated channels will be marked with an M - by hovering over the M a tip box will indicate the associated channels.
What if calls from additional channels don't show up in the user's End User Panel call logs?
In order for ipbx identify the calls from any additional channels as calls associated to an user, you will need to make sure the channel's Account Code field is set to the primary user/mailbox. So if you have for example an user with extension 44592 and a secondary channel 44692 you would set the Account Code to 44592@default. This will happen automatically if you create channels as described above, but needs to be set manually if you associate the channel after it has been created via the add channel functionality.