Question about using multiple IP phones for the same extension?

I’ve figured out how to use this. I started getting curious when my wife told me that her phone provided by 8x8 would allow her to transfer calls to her softphone from her desk phone with a simple * code. I’m just starting an implementation of Asterisk 13 w/Freepbx, and will be needing this feature in order to transfer calls to my cordless phone (probably cell phone with a softphone app), in order to walk around the building and not be tethered to my desk.

As stated by jfinstrom, make sure Max Contacts (within Extension) is >1. In my case, the default is 5. I’ve connected 3 phones to my extension. A phone at home, my phone in my office at work, and my mobile. If I am on a call and need to switch to a different phone, I simply transfer the call to my own extension (114), and the other two devices ring. Works out great.

“Device and user mode doesn’t exist don’t use it, things break and as we progress more things will break.”

I know people keep saying pjsip solves this, but doesn’t D&U mode also allow a sip device to share its extension number with a IAX device? I use IAX for my mobile extension because:
A) it gets attacked far less.
B) it requires just 1 Port forward
C) it seems to be more reliable at reregistering when I jump between wifi and 3G.

If d&u mode can mix an IAX and sip device on one extension number, surely that makes it more useful than pjsip?

I’m not positive what the motivation to respond to a 6 year old thread that hasn’t seen daylight in a year. This has been discussed extensively over and over. As much as I love the movie groundhog day I think we all know where this goes. Thanks for the input I’m going to do what should have been done 6 years ago and archive this