Misc. Dialplan Tools pickup
Basically the pickup endpoint is a dummy channel that never answers that you can originate to from anywhere you can place calls, call it alone or place it in a list for a forked dial.
Now the pickup channel will be created alongside the sip channel.
From another call route the call to the application pickup with data "mygroup" to have your channel return from originate
<action application="pickup" data="mygroup"/>
When you place that call, your session will be returned from the originate in place of the pickup/mygroup call being placed.
It also works with presence so you could assign blf buttons to it.
The group names can also have an @domain.com for multihoming etc.