What is the feature of a PBX system that creates a log of all incoming and outgoing calls?

The feature of a PBX system that creates a log of all incoming and outgoing calls is the Station Message Detail Recording (SMDR). SMDR is crucial in tracking call data, as it records detailed information about each call, including the date, time, duration, and the numbers involved. This data can be used for billing, reporting, and analysis of call patterns within an organization.

While other options have related functionalities, they do not specifically fulfill the same comprehensive tracking role as SMDR. Call Detail Record (CDR) is also a relevant term but generally pertains to recorded data more focused on network-side details rather than being dedicated solely to PBX-generated logs. Automatic Number Identification (ANI) primarily identifies the calling party's number rather than recording call details. Call Accounting often refers to the systems or processes used to manage billing and usage reports, but it does not itself create the log of calls; rather, it utilizes the data produced by features like SMDR or CDR.

Thus, SMDR is the best choice in this context for logging call information within a PBX environment.