The file is located in the /etc/asterisk/ directory.

By default, asterisk will generate a CDR for every finished call, this file defines what exactly gets logged in this CDR line.

By default the CDRs are stored in a CSV file in /var/log/asterisk/cdr-csv

This is available in asterisk head or version 1.2 only.



Let's have a closer look at the variables we can define here:

${CDR(clid)} = callerid for the call (with the name)
${CDR(src)} = callerid number for the call
${CDR(dst)} = destination extension
${CDR(dcontext)} = Destination context
${CDR(channel)} = Src channel
${CDR(dstchannel)} = Destination channel if appropriate
${CDR(lastapp)} = this is the last application in the dialplan used, on an outgoing call this will be DIAL.
${CDR(lastdata)} = these are the parameters given to the last application used in the dialplan
${CDR(start)} = time of the start of the call
${CDR(answer)} = time when the call was answered
${CDR(end)} = time when the call got hung up
${CDR(duration)} = duration of the call
${CDR(billsec)} = duration of the actual call (without the ringing)
${CDR(disposition)} = status of the call (ANSWERED, BUSY, NO ANSWER)
${CDR(amaflags)} = flag for the type of CDR (can be set in a.o. sip.conf)

${CDR(accountcode)} = the accountcode as set for this channel with for example SetAccountcode in the dialplan (Extensions.conf) or in the channel configuration file (e.g. per user in sip.conf, iax.conf and per channel in zaptel.conf)
${CDR(uniqueid)} = a unique id for this call
{CDR(userfield)} = a userfield set by the dialplan command SetCDRUserfield

As you can see, it is possible to define different "layouts" for different files.
The default file is Master.csv, but if you specify a different accountcode (with SetAccount or in sip.conf or iax.conf or zaptel.conf) the filename will change.

Related links:

cdr_manager.conf- disable or enable sending of cdr's to the manager interface