Dial No to 0870

You may have heard of the site Say No To 0870. It's a UK database of mappings of Company Names and their 0870/0844/0845 numbers to their geographic equivalents. Using the geographic equivlalents is a good idea - they're cheaper and included in a lot of plans' free minutes. Some companies can detect people calling their geographical numbers. Prefixing the number with 141 to withhold your number sometimes beats the system; sometimes it doesn't.

I thought it'd be a good idea to integrate the Say No To 0870 database with my Asterisk PBX, so that when I dial a number beginning with 08, Asterisk will actually call the geographical number with my Trunk provider. I achieved this using Asterisk AGI and Python. I screenscraped the Say No To 0870 website (theres no API, nor did they reply to my email) and untangled the HTML with Beautiful Soup.

If an 08 number has no entry, it just gets dialled. If there is an entry, it presents the user with a looping menu asking them to press 1 for the geographical number or 2 to dial the 08 number (in case the destination is smart, or the Say No To 0870 database is wrong). The script only considers the Main (Verified) numbers in the site's blue search results box.

You can view the script or, in Debian, you can install like so:
(Other distros store agi-bin in different places):

cd /usr/share/asterisk/
mkdir agi-bin
cd agi-bin
wget http://www.crummy.com/software/BeautifulSoup/download/BeautifulSoup.py
wget http://www.maniacmartin.com/files/noto0870.agi
chmod +x noto0870.agi
cd ../sounds
wget http://www.maniacmartin.com/files/mm-foundacheapernumber.gsm

Now, you need to add the following to the contexts in your /etc/asterisk/extensions.conf where you wish to allow users to dial 08-prefixed numbers:

exten => _08[4578].,1,AGI(noto0870.agi|${EXTEN})          ; Lookup in saynoto0870
exten => _08[4578].,2,Macro(dial-uk,0044${EXTEN:1})       ; If no match or user rejects, use normal UK trunk

The line for other UK numbers shouldn't accept 08 now. Something like this will do:

exten => _0[1237]XXXXXXXXX,1,Macro(dial-uk,0044${EXTEN:1})  ; Normal UK numbers

If a user chooses to use a cheaper number, the script will change the extension and jump to it on exiting.

Posted 13th October 2008 in Computer, with 0 comments