I noticed that when configuring feature codes I cannot specify a pattern that includes !. ! will match zero or more digits unlike . which requires atleast one more digit. This is extremely useful to make full use of some of the scripts thirdlane has put in place. For example *85 is already configured to use tl-check-voicemail. The tl-check-voicemail script is written so that more than 3 digits can be passed to it.
"If 3 characters are followed by extra characters, will treat them as a mailbox number otherwise uses caller's phone as a mailbox number."
instead of having to have 2 feature codes
exten => *85,
exten => _*85.,
one could merely have
exten => _*85!,
Another very useful place for this is 911 emergency calling. I would prefer
exten => _911!,
...over just 911 in the event a frantic 911 caller pressed an extra digit by mistake in the height of their panic.
911, coincidentally, is also why most advise against systems requiring someone to dial '9' to get an outside line. If they were to dial 9-1-240-555-1212, but accidentally pressed 9-1 and another 1 instead of 2, because they fat-fingered, they would have just made an emergency call :) and 9-911 is equally confusing when someone is panicked enough to need to call. Not that its relevant, just thought I would share.