Hi Pavel,
Here we go
Account Code Entry
The Cisco Unified IP Phones 7940 and 7940G and the Cisco Unified IP Phones 7960 and 7960G allow phone users to enter account codes during call setup or when connected to an active call using the Acct soft key. Account codes are inserted into call detail records (CDRs) on the Cisco Unified CME router for later interpretation by billing software.
An account code is visible in the output of the show call active command and the show call history command for telephony call legs and is supported by the CISCO-VOICE-DIAL-CONTROL-MIB. The account code also appears in the "account-code" RADIUS vendor-specific attribute (VSA) for voice authentication, authorization, and accounting (AAA).
To enter an account code during call setup or when in a connected state, press the Acct soft key, enter the account code using the phone keypad, then press the # key to notify Cisco Unified CME that the last digit of the code has been entered. The account code digits are processed upon receipt of the # and appear in the show output after processing.
No configuration is required for this feature.
Note 
If the # key is not pressed, each account code digit is processed only after a timer expires. The timer is 30 seconds for the first digit entered, then n seconds for each subsequent digit, where n equals the number of seconds configured with the timeouts interdigit (telephony-service) command. The default value for the interdigit timeout is 10 seconds. The account code digits do not appear in the show command output until after being processed.
Cheers!
Rob
