Someone in the PBX in a Flash forum wanted to know if there was some technique that could be used to get an e-mail alert if a user on the system dialed 911.  There are probably many ways this could be done, but here was the way I thought would work.  This has not been tested in a working installation so please note the disclaimer at the end of the article.  I DO NOT guarantee that this will work on your FreePBX installation!

EDIT (November 24, 2012): Another approach to doing this would be to add some custom dialplan to the [macro-dialout-trunk-predial-hook] context in extensions_custom.conf.  See How to use the FreePBX [macro-dialout-trunk-predial-hook] macro and regular expressions to blacklist or whitelist outgoing calls on all trunks for more information on this technique, which would allow you to easily detect outgoing calls to a particular number on just about any trunk with only a few lines of code, eliminating the need to create a CUSTOM trunk as shown below.  Either method will work, so do whichever you’re more comfortable with.

1. First, add a small additional context to /etc/asterisk/extensions_custom.conf (note that you will probably need to copy and paste this into a text editor to get the first line of the context complete and without line breaks where they shouldn’t be):

[custom-notify-email] exten => _X!,1,TrySystem(echo "This is to notify you that ${CALLERID(name)} at ${CALLERID(num)} has called 911" | mail -s "911 call notification" you@youraddress.com)
exten => _X!,n,Goto(from-internal,0000${EXTEN},1)
exten => h,1,Macro(hangupcall,)

Note that the first line of the context (not counting the context label line) contains the actual email to be sent.  Replace the various elements of the e-mail (body, subject, destination address) with appropriate elements for your situation. In the second line of the context, note that I’m prepending a four-digit code of  “0000” to the number dialed before sending it back into the dial plan.  This code can be anything you want and any number of digits you want, but it should start with something that a user would never dial when making a regular call.  Therefore, things like “0000”, “111111”, or even “*****” could be good choices, while “9876” would be a poor choice because a user might actually attempt to call a number such as “987-6911”.  One PBX in a Flash forum user reported that “0000” conflicted with Astridex in some way, so that’s why I’m taking pains to explain this.  Since the user isn’t expected to dial these digits, you could even use something like “010100001111”, just as long as it’s a code used uniquely for this purpose.

2. Create a CUSTOM trunk. Make the trunk name whatever you like, but for the Custom Dial String use:

Local/$OUTNUM$@custom-notify-email

When you set it up it should look like this:

3. Assuming you’re using this to monitor 911 calls, create a NEW emergency 911 Outbound Route that duplicates your existing 911 route (In FreePBX 2.9 or later you can click on the “Duplicate Route” button). In the duplicate (which should be right underneath the original in priority) change the dial pattern from 911 to 0000|911 (but if you used something other than 0000 in step 1, use the same thing here).  What this does is strip off the digits that were prepended to the number by the custom-notify-email context — this is done so you don’t create an endless loop. Note the pattern I have shown assumes you are using FreePBX 2.7 or earlier OR are using the Swiss Army Knife module to restore the pre-2.8 dial pattern text box in your Outbound Routes — if you haven’t done that then be sure you get each component of the dial pattern in the correct little box.

4. In your ORIGINAL emergency 911 Outbound Route, change the trunk selection to use only the CUSTOM trunk you created in step 2.

That’s it. The call flow is as follows:

Someone dials 911, it goes to the original 911 outbound route, then to the custom trunk and from there to your custom context which sends the email, prepends 0000 (or the digits you have used instead) onto the number (for example, making it 0000911 internally), and sends it back to the from-internal dial plan. It hits the duplicate 911 outbound route which strips the prepended digits and sends the call to your original trunk selection for 911 calls.

I would STRONGLY urge you to make a test call and see if it all works as you expect, if your local 911 service allows you to do that (call them on the non-emergency number first to make sure it’s okay). See the disclaimer below!!

You could use this same technique for non-emergency calls, but you’d have to have an Outbound Route dedicated to just those calls (in other words, it should only contain dial patterns for the calls you are trying to monitor, and it needs to be higher in priority than any other Outbound Route that might ordinarily handle such calls.  Once you have that working you can apply the above technique, which among other things means you’ll be making a duplicate of that Outbound Route, and making adjustments to the original and the copy as described above.

Disclaimer: The above is just a suggestion of what SHOULD work, and should be considered UNTESTED. Do NOT rely on it until you have tested it yourself to make sure it works as you expect. I don’t guarantee it will do anything except take up more space on your hard drive, so it is solely up to YOU to make sure it works as you want.

Related articles

• How to use the F – PBX [macro-dialout-trunk-predial-hook] macro and regular expressions to blacklist or whitelist outgoing calls on all trunks (tech.iprock.com)
• Did you know that Asterisk has the ability to evaluate Regular Expressions, though not in the same way as Perl or FreeSWITCH? (tech.iprock.com)