could u plz let me know the exact parameters which should i have to put in to chan_dahdi.conf to get (from pstn) CALLER ID work… Other things are working perfectly. 
Not based on the limited information that you have provided.
Which country are you in?
Who is providing your PSTN access?
Over what sort of interface?
What options have you subscribed to?
What interface card are you using?
etc.
Which country are you in? Sri Lanka
Who is providing your PSTN access? Sri Lanka Telecom
Over what sort of interface? FXO
What options have you subscribed to?
What interface card are you using? digium dtm400p
plzz send me the parameters which i have to change… thank you!
FXO isn’t precise enough and you didn’t indicate options. Even on loop start domestic lines, caller ID is optional in the UK, and there are two standards.
It’s possible that there is someone on the forum, in Sri Lanka, who knows that only certain possibilities exist, but for people in the rest of the world, we would need technical detail of the service being provided.
I don’t have the experience to actually answer, only to know that there is not enough information to answer, at least not without spending time researching the Sri Lankan telecoms market.