I am using mod_nibblebill but heartbeat doesn't fire after specified value. Here is my nibblebill.conf.xml file <configuration name="nibblebill.conf" description="Nibble Billing"> <settings> <!-- See http://wiki.freeswitch.org/wiki/Mod_nibblebill for help with these options --> <!-- Information for connecting to your database --> <param name="odbc-dsn" value="odbc://freeswitch"/> <!-- The database table where your CASH column is located --> <param name="db_table" value="users"/> <!-- The column name where we store the value of the account --> <param name="db_column_cash" value="balance"/> <!-- The column name for the unique ID identifying the account --> <param name="db_column_account" value="accountcode"/> <!-- Custom SQL for loading current balance - overrides column names channel vars are interpreted. field nibble_balance is used for balance info <param name="custom_sql_lookup" value="SELECT cash AS nibble_balance FROM accounts WHERE account_code='${nibble_account}'"/> --> <!-- Custom SQL for loading current balance - overrides column names channel vars are interpreted. nibble_increment is the amount to update <param name="custom_sql_save" value="UPDATE accounts SET cash=cash-${nibble_increment} WHERE account_code='${nibble_account}'"/> --> <!-- Default heartbeat interval. Set to 'off' for no heartbeat (i.e. bill only at end of call) --> <param name="global_heartbeat" value="5"/> <!-- By default, warn a caller when their balance is at $5.00. You can set this to a negative number. --> <param name="lowbal_amt" value="5"/> <param name="lowbal_action" value="play ding"/> <!-- By default, terminate a caller when their balance hits $0.00. You can set this to a negative number. --> <param name="nobal_amt" value="0"/> <param name="nobal_action" value="hangup XML default"/> <!-- If a call goes beyond a certain dollar amount, flag or terminate it --> <param name="percall_max_amt" value="0.001"/> <param name="percall_action" value="hangup"/> </settings> </configuration> After works perfectly after i set heartbeat from fs_cli for current session. Why heartbeat is not being fired from nibble.conf.xml file.? Thanks in advance.!