Asterisk 101: Some CallerID Tips & Tricks

If you're relatively new to Internet Telephony and VoIP, then it may come as a bit of a surprise when CallerID for incoming calls shows the phone number for both the name and number of the incoming caller or when names that popped up using your plain old telephone's CallerID service no longer do. The problem is that most telephone providers only deliver a CallerID number when sending calls. Thus it is left to your service provider to look up the incoming number in a directory and supply the matching name. To put it another way, CallerID numbers are pushed to recipients, but CallerID names must be pulled from in-house databases. With Ma Bell and siblings, this was easy because they had all of the records. With some Internet Telephony Hosting Providers, it's a different story. The reverse is also problematic. Even though you may provide a CallerID name and number, most telephone companies throw the supplied CallerID name in the bit bucket and do their own lookups. So... if you're not in their directory, your number or nothing will be supplied instead of your actual name. Just another last vestige of monopoly preservation. With Asterisk®, the simplest solution to this mess is to do your own lookups. And today we have an updated CallerID directory lookup service to assist: the CallerID Superfecta.

NOTE: This article has been superseded. Continue reading the latest article here.

We have a second utility as well. Since moving to PBX in a Flash and Asterisk 1.4 and 1.6, we haven't provided a simple way to block or screen anonymous calls, i.e. those that show up in CallerID as either blank, anonymous, unknown, private, restricted, or toll free number. As they say, those are the usual suspects when it comes to weeding out unwanted callers. And today we'll provide several solutions from which you can choose. Our personal preference is to never answer these calls and route them straight to voicemail. You may be more curious than we are so we'll show you an option to screen calls using the Asterisk Parking Lot feature. Still others may hate these callers so much that you send them into IVR hell for hours at a time. And we've got some suggestions on that one, too.

Introducing CallerID Superfecta. We've dusted off an oldie but goodie today and reworked it a bit for newer versions of PHP. We also want to thank taiter and M Joyner for their whitepages.ca contribution to what used to be our CallerID Trifecta. The CallerID Superfecta now lets you choose up to four CallerID lookup sources for your incoming calls. The sources include the Google Phonebook, AnyWho, WhitePages, and our very own AsteriDex address book and robodialer. Complete installation instructions are available from our Best of Nerd Vittles site.

Installation and setup is a snap on all of the FreePBX-based aggregations including PBX in a Flash, Elastix, and trixbox. First, download and unzip the callerid.zip file into the root directory of the web server on your Asterisk system. Next, configure the sources you wish to use in callerid.php by setting the desired sources to 1 instead of 0 on the second page of the file. Then define the new CallerID Lookup Source in FreePBX. And finally, select the CallerID Superfecta as the lookup source for each of your Inbound Routes. The whole setup should take you less than two minutes. Now sit back and enjoy a much enhanced CallerID experience when incoming calls arrive on your Asterisk server.

Introducing the Creep Detector. Well, not so fast. The CallerID Superfecta doesn't get rid of the creeps that call wanting to sell you something or urging you to vote for your favorite Coroner. For that, you'll need a couple of tools. FreePBX includes an excellent web-based implementation of the Asterisk Blacklist. It allows you to specify the phone numbers of calls that should be blocked. You also can do this with a phone on your system by dialing *32 to blacklist the last caller or *30 to blacklist a specific phone number.

But, what about blacklisting all of those anonymous callers. Well, there's not an existing function in FreePBX to do it. Our preferred method goes like this. When an incoming call arrives, a message plays saying "Thanks for calling the Mundy's. Please hold a moment while I connect your call." During this message, a Stealth AutoAttendant will allow family members to press various buttons to be connected to various extensions. See the previous article for details. Once the IVR times out (in about 5 seconds), the call is passed to a Privacy Checker which screens the calls for creeps. If the call isn't identified as such, it is sent to a ring group. If a creep is detected, the system first plays a message that says: "Press 8 to be connected." If no key is pressed, we hang up. If 8 is pressed, the call goes to voicemail 704. If 4 is pressed, the call is passed to the ring group. This lets friends calling from phones with CallerID blocked still get through the maze.

So here's how to get it installed and working. Log into your server as root and add the following code snippet to the bottom of /etc/asterisk/extensions_custom.conf:

[custom-privacy-check]
exten => s,1,SetMusicOnHold(default)
exten => s,2,GotoIf($["${CALLERID(num)}" = ""]?s,16)
exten => s,3,GotoIf($["foo${CALLERID(num)}" = "foo"]?s,16)
exten => s,4,GotoIf($["${CALLERID(name):1:8}" = "nonymous"]?s,16)
exten => s,5,GotoIf($["${CALLERID(name):1:6}" = "nknown"]?s,16)
exten => s,6,GotoIf($["${CALLERID(num):1:6}" = "rivate"]?s,16)
exten => s,7,GotoIf($["${CALLERID(name):1:6}" = "rivate"]?s,16)
exten => s,8,GotoIf($["${CALLERID(num):1:9}" = "estricted"]?s,16)
exten => s,9,GotoIf($["${CALLERID(num):0:4}" = "PSTN"]?s,16)
exten => s,10,GotoIf($["${CALLERID(num):1:3}" = "oll"]?s,16)
exten => s,11,GotoIf($["${CALLERID(name):1:2}" = "--"]?s,16)
exten => s,12,GotoIf($["${CALLERID(name):0:1}" = ","]?s,16)
exten => s,13,GotoIf($["${CALLERID(name):1:3}" = "oll"]?s,16)
exten => s,14,GotoIf($["${CALLERID(num):0:3}" = "000"]?s,16)
exten => s,15,Dial(Local/777@from-internal)
exten => s,16,Playback(custom/nv-press8)
exten => s,17,Set(TIMEOUT(digit)=10)
exten => s,18,WaitExten(10)
exten => s,19,Hangup
exten => 4,1,Dial(Local/777@from-internal)
exten => 4,2,Hangup
exten => 8,1,VoiceMail(704@default)
exten => 8,2,Hangup

You'll need to make a couple of changes in the code above before using it. In lines s,14 and 4,1, modify extension 777 to reflect an extension or ring group on your phone system that you want to call after incoming calls are screened for creeps. In line 8,1, modify 704 to reflect a voicemail box that is active on your system and that should be used for recording messages from unwanted callers.

The next step is to add the "Press 8 to be connected" message to your system. While still logged in as root, issue the following commands:

cd /var/lib/asterisk/sounds/custom
wget http://bestof.nerdvittles.com/applications/callerid/nv-press8.wav
chown asterisk:asterisk nv-press8.wav
chmod +x nv-press8.wav


Now we need to configure your FreePBX setup to use the code above. The easiest way is to modify your Stealth AutoAttendant IVR and simply change the timeout destination (t) to a Custom App: custom-privacy-check,s,1. Save your changes and reload your dialplan, and you're all set.

Some additional ideas have also been floated on the PBX in a Flash Forum for handling anonymous callers. If you'd prefer to park these calls and announce them, see this thread. And here's an embellished version that gives you options to accept the call, send it to voicemail, or banish the caller. Enjoy!

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