Caller ID with Google Voice and Asterisk 1.8

Previously it was possible to do a lookup of your contact's name against the numbers in your GMail/Google Voice contact list and apply that to your CallerID via John Baab's method outlined on his blog.

I've since then discovered that since updating to Asterisk 1.8 with native Google Voice this no longer functions.  This is because the format of the CallerID string that is sent from incoming calls is now different.

The entire string is sent in the "Name" field of the caller ID.
For Voice Calls, this is what it looks like:
+18475551212@voice.google.com/srvres-MTAuMTIuMTM4LjI2OjD4NdM=
For calls coming in from Talk or GMail, this is what it looks like:
user@gmail.com/gmail.424BF12F

Fortunately, this entire field can be processed using built in asterisk functions to extract the data we need, restoring the functionality of John Baab's script.

Here's all the steps that i've taken to add Caller ID support:

1) Install python, python-expat, python-openssl
opkg install python python-expat python-openssl

2) Fetch John Baab's script and place it somewhere useful.
wget http://www.baablogic.net/googlecontacts.py


3) Download gdata-python from http://code.google.com/p/gdata-python-client/
wget http://gdata-python-client.googlecode.com/files/gdata-2.0.12.tar.gz


4) Manually install it.  The setup.py script doesn't work on OpenWRT, so this method can be used:

tar xzzf gdata-2.0.12.tar.gz
cp -r gdata-2.0.12/src/* /usr/lib/python2.6/site-packages/
rm -rf gdata-2.0.12*

5) Modify John's script to include your gmail login information.  Run it once manually to populate your database
./google-contacts.py

6) Modify your [google-in] context to process the number properly and do a database lookup:

[google-in]
exten => superm1@gmail.com, 1, NoOp(Callerid  ${CALLERID(name)})
exten => superm1@gmail.com, n, Set(CALLERID(num)=${SHIFT(CALLERID(name),@)})
exten => superm1@gmail.com, n, Set(CALLERID(name)=${DB(cidname/${CALLERID(num)})})
exten => superm1@gmail.com, n, Dial(SIP/101, 180, D(:1))

7) (optionally) Add this to your crontab so that it will sync new numbers on a regular basis.  John's script will actually redo the database on every run, so it will also get updates then for every removal too.

crontab -e

This will only take effect for calls routed in through google voice or talk because we only modify the google-in context.  If there is no data available, the name field will just remain empty and the number will be shown on Caller ID instead.