To clarify, with RingDelay set to 0, the phone started ringing immediately with no caller ID, but caller ID showed up after the second or third ring. Basically, my phone was behaving the same as if it wasn't connected to an Obihai at all, which is what I was trying to achieve.
However, it recently stopped working - the caller ID never shows up anymore for calls coming in on the PSTN line.
Any suggestions on how to fix this (for those who were actually able to get it to work).
The frustrating thing with my Obi is that even though I don't change any settings, things always seem to stop working properly.