I have tried this:
[from-internal]
exten => _4XX,1,Dial(SIP/${EXTEN})
same => hint,SIP/${EXTEN}
After reloading dial plan, core show hints only showed the "unexpanded" hint.
This forced me to define the hint explicitly like this:
[from-internal]
exten => _4XX,1,Dial(SIP/${EXTEN})
exten => 400,hint,SIP/${EXTEN}
exten => 401,hint,SIP/${EXTEN}
exten => 402,hint,SIP/${EXTEN}
....
The only information I was able to find on this was the following which implies this must be possible.
Asterisk 1.6.1.x: It is now possible to specify a pattern match as a hint. Once a phone subscribes to something that matches the pattern a hint will be created using the contents and variables evaluated.
-https://www.voip-info.org/asterisk-standard-extensions/
What is the correct syntax for creating hints using pattern matching?