Hi,

Yes, the DTMF digits detected are the correct caller id.
This line is in India from a telco called Airtel.
I think caller id is being sent via DTMF. Based on what I've read on
various forums, from people trying to get it to work on sipura devices
or dahdi with asterisk, Airtel uses polarity reversal to first alert
the other end to pick up caller id and then sends it via DTMF.
I'll try and confirm this soon.