It is used mainly with DOCSIS and DSL carriers, by encapsulating PPP frames in ATM AAL5.
Point-to-Point Protocol over Asynchronous Transfer Mode (PPPoA) is specified by The Internet Engineering Task Force (IETF) in RFC 2364.
[1] It offers standard PPP features such as authentication, encryption, and compression.
The use of PPPoA over PPPoE is not geographically significant; rather, it varies by the provider's preference.
ATM configuration includes: ATM configuration can either be performed manually, or it may be hard-coded (or pre-set) into the firmware of a DSL modem provided by the user's ISP; it cannot be automatically negotiated.