The trouble with PSTN lines is that the CID has to be transmitted in-band, and there are more than one standard in doing this. On top of that, there are small differences between the various Telcos on the planet. And finally, to make things worse, documentation about it, is sparse and scattered at best.
The settings displayed usually go in /etc/asterisk/zapata.conf (either directly, or by inclusion).
How CID is handled is defined by the following variables:
The following settings have been verified to work on a Belgacom Twin line (one ISDN, interfacing to two PSTN lines), with a Digium TDM400p:
callerid=asreceived cidsignalling=dtmf cidstart=ring sendcalleridafter=0