twilio/twilio-python — pull request #49 by sammachin (2012-03-06 08:42:42+00:00)
Title: Added support for callerId on Dial verb in twiml response

http://forum.twilio.com/twilio/topics/twilio_python_dial_verb_cant_set_callerid

I've added a fix for this myself, its needed so I can initiate calls from a client as the callerId param there is mandatory.
Had a go at writing a test and it seems to pass but TDD isn't my strong point :-)