Is there a way to configure user access codes for making Long Distance calls on a Call Manager Express version 4.1, or 3845 based voice gateway?
Just to add to Jasons excellent info, In conjunction with After Hours configuration you can use Pin Codes and "Call Blocking Override" that as close as it gets with CME. Have a look, it may be quite workable;
The after-hours configuration applies globally to all dial peers in Cisco Unified CME. You can disable the feature on phones using one of three mechanisms:
directory number - To configure an exception for an individual directory number.
phone-level - To configure an exception for all directory numbers associated to a Cisco Unified IP phone regardless of any configuration for an individual directory number.
dial peer - To configure an exception for a particular dial peer.
Individual phone users can be allowed to override call blocking associated with designated time periods by entering ***personal identification numbers (PINs) that have been assigned to their phones. For IP phones that support soft keys, such as the Cisco Unified IP Phone 7940G and the Cisco Unified IP Phone 7960G, the call-blocking override feature allows individual phone users to override the call blocking that has been defined for designated time periods. The system administrator must first assign a personal identification number (PIN) to any phone that will be allowed to override call blocking.
Logging in to a phone with a PIN only allows the user to override call blocking that is associated with particular time periods. Blocking patterns that are in effect 7 days a week, 24 hours a day, and they cannot be overridden by using a PIN.
When PINs are configured for call-blocking override, they are cleared at a specific time of day or after phones have been idle for a specific amount of time. The time of day and amount of time can be set by the system administrator, or the defaults can be accepted.
From this excellent doc;
Hope this helps!