Tag: Digium

Asterisk hiding a useful feature in plain sight by giving it a "cute" name


This is an edited version of a post that originally appeared on a blog called The Michigan Telephone Blog, which was written by a friend before he decided to stop blogging. It is reposted with his permission. Comments dated before the year 2013 were originally posted to his blog.
easter eggs in the stage of painting
Easter Eggs (Image via Wikipedia)

Somewhere in FreePBX 2.7 or thereabouts, it became know that there was a feature of FreePBX Outbound Route dial patterns, were you could use a /CallerID extension. This (among other things) basically lets you limit the use of an Outbound Route to a particular extension or group of extensions.  It’s a very useful feature, but wasn’t widely announced or promoted at the time.  I finally figured out why.

Thing is, it’s NOT a FreePBX feature, it’s a feature of Asterisk.  Anywhere in an Asterisk dial plan where you have a line that starts with

exten => _somepattern,…

you can use the Caller ID modifier, like this:

exten => _somepattern/callerid,…

In which case the pattern won’t be matched unless the current Caller ID number (which on an internal call is the number of the calling extension) matches whatever you’ve replaced callerid with.  Callerid can itself be a number or a pattern.

The real kick in the head is that it appears this feature has been around for a LONG time.  It was definitely in Asterisk 1.4.  Yet virtually none of the documentation you see on Asterisk even mentions this feature.  It might as well have been an “Easter Egg” hidden in the software, for all anyone knew of it.  Well, I finally figured out why — the Asterisk folks hung a “cute” name on it, and it stuck.

They called it ex-girlfriend logic.  The idea is that you can use it to stop an ex-girlfriend from bothering a particular user on your system (at least in raw Asterisk, though I don’t think that’s directly supported in FreePBX).  Besides being a bit sexist, it’s also about the last terminology anyone would think to Google on if they were trying to find out about this feature.  So while people were writing third-party modules like Custom Contexts and Outbound Route Permissions in FreePBX, it now turns out that essentially the same basic functionality was there all along, but hardly anyone (at least in the FreePBX world) knew about it until around about the time of FreePBX 2.7 or so.  If you can find anything at all about this feature in “official” Asterisk documentation (that doesn’t include third-party sites!), you’re a better searcher than I.

Makes you wonder if there are any OTHER cool features in Asterisk that are hidden in plain sight, under unfortunate descriptive names that no one would ever think to use when searching for such a feature!


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